Before proceeding with such drastic action as reformatting, I would try giving your PC a scan with Prevx1. I've used and recommended this on many occasions where other products have failed, so it's certainly worth a try. This is a pay-for program, but they offer a free trial which will remove any infections free of charge during this period. If you don't wish to keep this after scan and any cleanup you can simply uninstall it.
If this doesn't work either, I would still consider running a HijackThis log and getting an expert to look for anything suspicious? Reformatting really should be a final resort - and although CSRSS.EXE looks like it's causing the issue, there may also be another file/process instigating this.