My computer is very slow at this moment and I can see in the Windows taskmessenger that the proces ROC_JAN2013_TB.exe use 98% of my CPU.
What is this? A virus? How can I solve this problem?
For the record I use Avast free antivirus
That file belongs to the update process of AVG so I think your on the wrong forum 
if you have AVG installed with avast you need to remove AVG as you cant have two antiviruses installed on the same system together.
http://systemexplorer.net/file-database/file/roc_jan2013_tb-exe/17668404
run uninstall tool for the AV you remove so that all files are gone