You need to be using Service Pack 2 on your machine......
Click Control Panel
Click the "Advanced Tab"
click the "Settings" button under "Performance"
Click the "Data Execution Prevention" Tab
Click the option for "Turn on DEP for all programs except those I select:"
If nothing appears in the box below, click the "Add" button and browse to the offending .exe file
If you can't locate the offending file then just recheck the "turn DEP on for all programs option and OK out
DEP errors are mostly spyware/malware and or virus scripting attacks. Clean your temp files prefetch files and all caches then run your anti malware/spyware programs again
A good Temp file cleaner is:
ATF cleaner |MG| ATF Cleaner 126.96.36.199
You can also go to this site and read up on the errors! Data Execution Prevention (DEP) - Windows XP Service Pack 2