|If it did run fine then assume software error first.|
Most likely tasks are using resources or drivers are causing problems.
In some cases leaving wireless on with strong encryption is using a lot of resources. Junk transmissions most of it.
The best thing to start with is running perfom on a remote computer or locally to see what is using resources. See also taskman and see programs and apps such as systernals to see what is really going on.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10