at start up mesage displays can not find svchost.exe what should i do

Is this a new issue? Any new hardware or software? Any problems besides this?

What happens after the message? Can you start XP normally?

svchost.exe is a generic service host service. There are usually about six such services that start with XP plus others added by third party software.

You can go to start Run... msconfig | Startup and selectively edit what software starts with Windows. By trial and error you might be able to ID the software that is throwing this error.