Yes, do what Zlator says and check for recent updates... and possibly remove them. If you get automatic updates from M$ I know they just pushed out another genuine advantage app for office with their last batch of useless updates; it might be causing an issue. (I look at each KB article for every patch to find that most of them are indeed useless, so yes, my statement is qualified.)
Other than patches, have you updated any Anti-virus/spyware/firewall software and/or ran a scan to detect malicious code? Any new software installed? and I do mean ANY new software whatsoever. Have you downloaded anything (such as ActiveX controls or plug-ins) from websites?
Does Word or Excel open by itself? (without opening a document) This will narrow down your problem to either the program(s) or the documents. If the former, re-install Office. If the latter, it might be infected and your virus scanner is preventing it from being opened.
Ken