First question. Are you using "Zone Alarm" If so, try disabling it and trying again.
I agree, if it's not Zone Alarm it's probably a similar firewall type program that is shutting down/blocking the execution .... I would run msconfig, if It will run from clicking start and typing it in... and uncheck everything that is running. Also the link in my tagline for identifying your problem may have an explanation in the logs for why programs are not running.
You may be in a situation where you can't even run any diagnostic programs or view logs, or even back up you personal files and such, in that case you can try to run in safe mode by pressing F8 and hopefully get backed up before you reinstall Windows.