Hi amethyst_iris, Welcome to TSF.
Could you tell us what process it is that is using most of the CPU?
To do this:
1. Open task manager (CRTL + ALT + DEL)
2. Open the Processes Tab
3. In the little table below, click the CPU
4. If the top numbers in the column are 00 (zero's), click it again, if not, post back the names of a few of the top most processes.