With no error message it's going to be very difficult to troubleshoot. You could check the Windows event log viewer to see if there is anything interesting there I suppose.

generaly speaking if games wont launch and you may find some other software may not lauch either then the problem may be one of 2 things
first your machine is infected with a virus or malware
this is less likely if your install of windows is new but it realy depends on what sites youve been visiting and what youve installed
scan your machine with your usual antivirus and maware tools. if your machine is badly infected the best option is to reinstall windows

second theres a problem with your windows install or something you have installed
assuming this is not caused by the first option run a system restore, 9 times out of 10 this will resove the issue if the software worked before

try restarting your machine with a selective startup, using msconfig (start search msconfig) untick load startup items, this may identify if something youve installed is causing the problem. althogh it may not eliminate software firewalls or your AV as the cause.. try using diagnostic startup as a last resourt if your pc is not connected to the www, but this will give you more of an idea if the problem is cause by software installed on your PC

try creating a new windows logon preferably with admin level access. if this works then your install of windows is in bad shape. the fix with XP it was simply a case of recreating and deleting accounts, with w7 its not quite so easy. try running SFC (system file check) from an admin command prompt type SFC /scannow
or repair using your windows install disk although imho this tends to only put a plaster on the wound, it dosent actualy cure the underlaying problem

also try a reinstall of windows, even if you use a dual boot with the same OS, instal drivers only and the software your having a problem with then test and only after testing install other softare patches and service packs