[Remote Login Issue] Expired Security certificate

[SafeBett]

Hi guys, i am having a small (and newly developed) issue with 1 of 4 computers and cant seem to figure why.

Comp #1 Windows 98 SE 16 bit FAT
Comp #2 Windows XP Pro 32bit NTFS
Comp #3 Vista Premium 64bit NTFS
Comp #4 Windows 7 MC 32bit NTFS

Before NYE all where able to connect remotely to the server, when i returned from 2 days break Comp #3 will no longer connect and displays a warning that the certificate has expired.

And as luck would have it, the #3 Comp is the newest/most powerful

The solution is probably staring me in the face, but i cant see it.

Any Idea's?

Thanks in advance