Can't login to account. Error: Windows Security - An Internal Error Occurred.

I've been at this one over a week but I haven't been able to resolve it.
When trying to login to my account one morning I received the following error:

Windows Security
An internal error occurred. Please contact your system administrator.

I can log into safe mode andI've tried several different methods to resolve this error, but to no avail. The following are in reference to trying to log into windows vista home premium normally, as in I receive the above error just after clicking on the account icon. I've created two new accounts, one password protectedand one not and each receives the error. I enabled the administrator account but received the error. Iuninstalled iTunes (the last thing I changed before I went to bed the night before) but still receive the error.I tried doing startup repair several times but no joy (it says it cannot find any problems). I tried going the last known configuration and system restore point route but didn't get anywhere with that either.

One thing that I have found somewhat works is using the Directory Services Restore Mode. This lets me boot into what seems like a more capable safe mode, but I don't think its a long-term solution. I'd like to not have to do a complete system restore so any help as to how to fix this problem would be greatly appreciated.