Can't open files after Office XP service pack install

[Adam]

I installed SP-1 and SP-2 and can no longer access any
files in Excel or Word. In Word I get the following
message, "The [file name]is not available". In Excel I
get the following message, "Unable to read file". I then
ran the office update detection application and installed
various updates (Office XP, Outlook, and Excel, including
security packs). None of that worked and the files still
do not open.