Definite Malware activity. There are these usb infectors that will stop you from viewing hidden files. I would suggest u to download AMIR from MalwareInfo.Org and detect if any infected files are there. If you are running any AV Client then update that with the latest definition and disable system restore and run a full system scan from Safe Mode... if the malwares signature is in ur AV Definition, then it will reslve the issue by cleaning the malware... else I would recoment you to take the help of someone who knows how to clean undetected malwares from the system... also you can post your system log generated with AMIR in www.malwareanalysis.org.
P.S: Show hidden files not working or Folder Options Missing, can be a definite sign of malware activity. Anyone facing this problem should consult a person who is having good idea and knowledge about cleaning undetected malwares from system.
