Open Task Manager processes tab and determine which processes are using the most memory.
You have one or more of the following.
1) Incorrect virtual memory settings.
2) A lot of unnecessary programs running
3) Bad system file(s)
4) Malware on your system
1) Incorrect virtual memory settings.
Windows Knows Best per:
http://askbobrankin.com/low_virtual_memory.html
If you still see the dreaded "Your system is low on virtual memory" message then the first thing to do is make sure your computer is configured to allow Windows to automatically manage the virtual memory. In Windows XP, follow these steps:
Click Start, then open the Control Panel.
Click Performance and Maintenance, and then click System.
Click the Advanced tab.
Under Performance, click Settings.
Click the Advanced tab.
Under Virtual memory, click Change.
Under Drive [Volume Label], click the drive that contains the paging file (virtual memory) settings that you want to change. In almost every case, this will be your C: drive.
Click to select the "System managed size" option, then click Set.
Click OK three times and restart your computer.
When you allow Windows to manage your virtual memory, it should make the optimum amount of virtual memory available, by automatically shrinking or enlarging the paging file as needed.
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2) A lot of unnecessary programs running
Run PC Pitstop "full tests"
http://www.pcpitstop.com/
In the results the "running programs" section will list "programs that can be disabled to improve computer performance". Run msconfig and uncheck the boxes for these programs.
Using MSCONFIG to reduce background programs at startup
http://alri.org/step2/usingmsconfig.htm
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3) Bad system file
Run "check disk" check both options and restart.
Run Disk Cleanup then Disk Defragment.
4 Ways to Speed Up Your Computer's Performance
http://www.microsoft.com/atwork/getstarted/speed.mspx
Install: User Profile Hive Cleanup Service
A service to help with slow log off and unreconciled profile problems.
http://www.microsoft.com/downloads/details.aspx?familyid=1B286E6D-8912-4E18-B570-42470E2F3582&displaylang=en
Start> Run> enter "sfc.exe /scannow" in the run box.
Run. You will need the windows XP disk. This utility will check all system files against the disk and repair if needed.
System File Checker (sfc.exe)
http://www.updatexp.com/scannow-sfc.html
http://www.networkclue.com/os/Windows/commands/sfc.aspx
http://support.microsoft.com/kb/185836
http://support.microsoft.com/kb/310747
If this doesn't work, you may need to do a repair install.
Repair install. (should not lose data) Backup files first.
http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/doug92.mspx
http://www.fujitsu-siemens.co.uk/rl/servicesupport/techsupport/software/windows/xp/Repair.htm
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4) Malware on your system
You might have malware installed on your system. If you follow all the following steps it should get rid of your problem and prevent future problems. All programs listed are free.
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Follow step 1:
Uninstall Malware from Windows Add/Remove Program Tab
http://www.techsupportforum.com/security-center/hijackthis-log-help/15968-updated-important-read-before-posting-log.html
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Update your antivirus and run a full scan
If you do not have virus protection install:
AVG Antivirus 7.5 Free Edition
http://free.grisoft.com/freeweb.php/doc/avg-anti-virus-free/lng/us/tpl/v5
or
Free antivirus - avast! 4 Home Edition
http://www.avast.com/eng/avast_4_home.html
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Install Windows Defender (full time spyware protection)
Perform a full scan.
http://www.microsoft.com/athome/security/spyware/software/default.mspx
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Install the following five programs and run weekly or at least monthly. You need all five. They are not a substitute for full time spyware and virus protection.
Install and run now.
Ad-Aware SE Personal (update + full scan)
http://www.lavasoftusa.com/products/ad-aware_se_personal.php
Spybot Search & Destroy (update + immunize + scan)
Do not enable Tea Timer and SDHelper
After installation: update + scan + immunize
http://www.safer-networking.org/en/mirrors/index.html
SpywareBlaster: Update then open and click “enable all protection”.
http://www.javacoolsoftware.com/spywareblaster.html
SUPERAntiSpyware free version: (update + scan)
http://www.superantispyware.com/
CCleaner: Do not install toolbar and recycle bin options
Removes tracking cookies, unneeded files, history
In options.
Set to run when computer starts.
Place cookies you want to keep in save list
http://www.ccleaner.com/
Note if a scan detects a problem but is unable to remove, start the computer in safe mode with the internet line disconnected and run a full scan.
In severe cases your system restore files will also be infected. In these cases you will need to turn off system restore to prevent malware hiding in the system restore files and reinfecting the computer during removal or during a future system restore. Turning off system restore deletes the system restore files.
Right click on "my computer"> Properties > System Restore Tab > Check box turn of system restore
After the malware is removed turn on system restore.
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Run this time
Install VX2 tool for Ad-Aware and run tool
http://www.lavasoftusa.com/support/securitycenter/vx2_cleaner.php
CWShredder: run
http://www.trendmicro.com/cwshredder/
SmitFraudFix
http://www.geekstogo.com/forum/How_to_use_SmitFraudFix-t109268.html
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Additional run this time and as needed.
Microsoft OneCare Live, run “full service scan”
Updates windows, virus and spyware scan, disk cleanup, disk fragmentation (if needed), backs up registry and then cleans registry, and checks for open firewall ports
http://onecare.live.com/site/en-us/default.htm
Malicious Software Removal Tool (run “full scan”)
http://www.microsoft.com/security/malwareremove/default.mspx
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Rootkit Removal Guide
http://safecomputing.umn.edu/guides/scan_unhackme.html
Rootkits Removers (Pick any 2 install and run monthly)
AVG Anti-Rootkit
http://www.grisoft.com/doc/products-avg-anti-rootkit-update-app-art/?ver=1.1.0.29
F-Secure BlackLight
http://www.f-secure.com/blacklight/
Sophos Anti-Rootkit
http://www.sophos.com/products/free-tools/sophos-anti-rootkit.html
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Online Free Scanners:
Run Trend Micro, Kaspersky, and Panda Scan now.
Run a different one each month.
Trend Micro: HouseCall Free Scan (removes what it finds)
http://housecall.trendmicro.com/
BitDefender Online Scanner http://www.bitdefender.com/scan8/ie.html
Kaspersky Labs Online Scanner http://www.kaspersky.com/virusscanner
McAfee http://us.mcafee.com/root/mfs/default.asp?affid=294
Panda ActiveScan Free Online Scanner http://www.pandasoftware.com/products/activescan?
Symantic Online Scanner http://security.symantec.com/sscv6/ssc_eula.asp?langid=ie&venid=sym&plfid=23&pkj=ALUFRHYTINMHDKDCWLL&vc_scanstate=2
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Additional Information read:
http://wiki.castlecops.com/Malware_Removal_and_Prevention:_Overview
http://wiki.castlecops.com/Malware_Prevention:_Prevent_Re-infection
http://www.castlecops.com/f67-Hijackthis_Spyware_Viruses_Worms_Trojans_Oh_My.html
http://aumha.org/a/quickfix.htm
http://aumha.org/secure.htm
http://aumha.org/a/parasite.php
http://www.castlecops.com/t102301-Hijackthis_Guidelines_Read_Before_Posting.html
http://www.techsupportforum.com/security-center/hijackthis-log-help/15968-please-read-before-posting-
http://forum.aumha.org/viewtopic.php?t=4075&sid=901703d08c2ace31389ffef2d84b6607