I just installed CCleaner v.3.22.1800 (64bit), and it crashed my Windows 7 (64bit) systemon first use!
Analysis had come up with c. 30 MB of files to be cleaned. When I ran the Cleaner, the system crashed to the BSoD.
How do I go about diagnosing this problem?
Should I just go back to a previous version of CCleaner?
If it was a BSOD there will be info on your machine about it.
The Windows Event Viewer should list it, and there may be a minidump file in C\minidump.
If you download Blue Screen Viewer or WhoCrashed, either of them should give you info on the cause. perhaps you would like to run it and post what it says here in this thread.
http://www.nirsoft.net/utils/blue_screen_view.html