svchost is the service host for Windows, so more then likely a service is failing at startup. Go into msconfig (enter msconfig in the run menu) and in teh services tab, uncheck any services you aren't using/don't want enabled.
OK - As Gamer pointed out, svchost.exe is a generic windows process which may be used by any number of applications and drivers. So killing svchost.exe won't do you any good at all - Windows will jsut open another one as soon as whatever app requests it. So you have to dig deeper to see which application or driver is causing the problem.
How do you do that?
Give your computer the three finger salute (Control/Alt/Delete), and go into the Task Manager. Go to the PROCESS tab. In the lower left corner, select "Show Processes from All Users". Along with everything else, there will be some number of svchost.exe entries. Look at the usage to see which is likely to be the trouble. This will be easy because it'll be the one(s) with large usage.
Right Click on the suspect entry, and choose Service/s in the pop up menu. This will jump to the services tab, and all of the services under that svchost.exe will be highlighted. From there you simply identify what is what, and go fix/reinstall those.