Heather, a windows Repair replaces windows files and restores its registry settings, third party software files and reg entries are not affected so I think the problem may lie in that direction....
Because you mention Trillian it may be worth searching for and deleting these two WildTangent files which may have been installed along with Trilllian [bundled "spyware"]:
wtcpl.dll and wtcpl.cpl
May work, may not. The Repair was worth a try, at least it pointed the search in another direction.
Does going Start, run, typing control and pressing Enter work?