Jill it varies from system to system depending on what's running in the background for the antivirus to check but that would seem high. My systems average around 65000K.
For starters try checking for malware using Stinger and Malwarebytes Free both linked in the last link in my signature below.
Then make sure the OS is totally up to date in all aspects using the Microsoft Update option in Windows Update settings, including any parts that may not be normally used (a good example of this is people fail to keep IE and its add-ons up to date because they use another browser).
Make sure drivers are the latest.
Try running the Virtual Techcnician to see if it finds and fixes any flaws in the software: http://mvt.mcafee.com/
Warning: MVT may not find the software if it is provided by a 3rd party, in which case move on to the last option.
Contact Technical Support via the link under Useful Links at the top of this page - it's free by phone or online chat. They may be able to offer some suggestions.