repairing user accounts

I have an Windows XP computer with multiple user logon accounts. Most work but a few are messed up. For instance I can't view any webpages in IE (i get the page cannot be found error) also programs won't run in the start | run dialog box. But all these things work if I logon as someone else.

I did find the w32.welchia virus on the computer and removed it using Mcafee virus scan. but this did fix the problem. Is there a way to repair or rebuild indiviual user accounts??

 

Can you not just delete the accounts and recreate them?

*edit*
A little more info