I had previously mentioned the intrusive popup message to upgrade to AVG 9, so last night I decided the only way to avoid that irritation was to do the upgrade. Bad idea.
I thought that I had downloaded the upgrade & saved to my hard drive. But when I ran it, what I had was just a download manager which then took about 20 minutes to download the actual program. Very slowly - my Cox connection generally runs 8-10 Megs download speed, but their connection manager was reporting speeds of only 175K. That's with a "K".
The install ran OK on my HP desktop, but failed on my ThinkPad. Lucky me.
This morning I booted up the desktop to find that something was chewing up CPU and thrashing the hard drive. Turned out to be my brand-new AVG 9. I Google'd about & found lots of complaints, specifically mentioning avgchsvx.exe as the culprit. In some cases users would report that it ran for up to 2 hours upon boot-up.
Fortunately I had saved the 8.5 program on my disk, so I just uninstalled 9.0 and reinstalled the previous version, ran the Update Manager several times to get all the program & virus updates; all of which completed within 10 minutes.