Internet Explorer Error Message, msvcrt.dll

Okay, I recently had a few problems with malware, dealt with by Norton, Windows Defender, Spybot, and VundoFix.  Anyways, shortly thereafter, my father did *something* to my computer after seeing a pop-up.  He says he just deleted the browsing history on his account, but now whenever we boot Internet Explorer on any account, we get the "IE has encountered an error and has to close... sorry the inconvenience message".  Looking at the error message in more detail, we have:

Appname: iexplore.exe

Appver: 7.0.6000.16574

Modname: msvcrt.dll

Modver:  7.0.2600.2180

Offset:  00037740

 

After running Norton, Defender, and Spybot without getting any sign of malware, I tried system restore.  And now, I can access IE without any problem... but only on the first account I sign into after System restore (all other accounts get the error message), and if I restart or log off, I get the error message again.

 

EDIT:  If this helps any, I'm working on a Dimension 3000 with XP service Pack 2, and I've had this computer since 2004.  I've faced some issues (spyware); but this is the first time I've had this particular problem.  Also, after the error started appearing, Norton's intrusion protection blocked some attempts to attack my computer.