Did I just got a virus or what happened?

So I was browsing some mp3 sites and then my Windows 7 theme suddenly changed from black to blue. And PC stopped responding for a few seconds. After the reboot its all fine but did I get infected? My Avira shows no viruses
Answer #1
Irvine replied: did I get infected?
I don’t know, did you open some random file you downloaded?
If so, then you probably did =/
Irvine replied: My Avira shows no viruses
Avira is crap IMO. Use your head, and don’t download random crap =D
Try running a scan with Malwarebytes.
Answer #2
If it’s working fine, then you shouldn’t worry about it. Probably just a windows program crashing.
Answer #3
Download Malwarebytes Free and do a scan and you will find out