Security :: Virus Partially Disabling PC In Different Ways

Since about 4 days, I'm having various problems primarily on the internet.

1) All sorts of downloads from the internet first load normally, then stop at 99% and usually dont finish, some end 5 minutes later, resulting in a damaged file. Example: Downloading a song this way makes it randomly jump parts of the song in short intervals (a song of 3:50 minutes would then be in my itunes with a duration of 3:46 due to the random jumps); downloading CCleaner and similar programs did not work at all (not even a damage file).

2) Pictures on the internet become "puzzled" and colors change randomly. Example:

3) Only tested this on youtube - videos load 10x slower than before the issue + some flash plugin keeps crashing (also never happened before - even with 50+ tabs).

4) Frequently sites do not load (they stay white).

5) A "firefox update recommendation" and a "flash player update site" with untrustworthy URLs often randomly open, sometimes even 5 times in 5 seconds + I suddenly get overloaded with random advertisement from the left, bottom and right screen sides.

THE PROBLEM WAS A PLUGIN CALLED "NET-CRAWLER" >uninstalled it, and everything worked out.