I still have this problem, and I have faced it in most of the computers I fixed in this month. I have created a minidump, but how can I upload it to the FTP?
This has happen to computers brought back to life via Norton Ghost, and they are different chips and companies, some are AMD, some are Intel, but all of them are Windows 7 x86. Avast was 200 days or more out of date, and after updating the program this started to happen. The Ghost images are different dates and different sub versions of windows 7, I have tried a clean update as well, but the problem remains, as many have stated above, CPU goes to 100% for long time out of nowhere, no scan is being carried out and no shield seems to be responsible for the issue. the Dump has been made with Process Explorer.
EDIT: I learnt how to upload to FTP, I am in process of uploading the fulldumps to the FTP stated above.