im trying to open a file that i downloaded lastweek, last week it open no problem but now i get this stupid message

Packed data CRC failed. The volume is corrupt"

and its not just the 1 file either theres a few, it opened ok last time, ive unistalled winrar and reinstalled but its still the same, whats going on?

everytime i run rar different files fail

ps ive run quick par and all is fine, so im even more confused!