I suspect that my system has been hacked into. I see huge drops in free hard disk space for a while and then the space returns to near old values. A few days ago, when i clicked 'my computer', i saw the properties of the computer instead of 'my computer'. Start menu showed me the same thing. I rebooted my system and things became normal. All my browsers hang for a while. Additionally, sometimes my FB login page looked weird and unlike the regular page (Browser injection???) Then, there are these chinese alphabets in the attached image.
Is it possible that my system is infected with some stealthy malware? If yes, how do I check if it is really malware?
I am worried to death now. all the paid av, sandboxing, no-scripting finally might have amounted to nothing. :(
Thanks in advance.