Thanks for the reply, I think I mostly understand what you're getting at now.
But after doing all that you suggest, you say "test and report back." The thing is that the problem I'm trying to solve only happens occasionally, like this time it took a month for it to happen again (it used to happen more often like maybe once a week or couple of weeks), so I can't really just 'test and report back' right away because I have no idea how long it will take for this problem to occur again.
Also, since no one else here is having this problem, it indicates to me that this probably isn't an Avast problem--the only strange thing was that the last few times this happened Avast wasn't running after my computer started and I had to reboot to get Avast to run again, and then the time before this one Avast would not run at all, which is why I did the reinstall. That was the only time that happened that Avast wouldn't run at all.
This time Avast is still working fine after the problem happened yesterday, did not even have to reboot to get it to run.
About following the 'normal' procedure and boot into safe mode 'while I still can'--the thing is, I don't stay at my computer while it's booting up, I just come to back to my computer after it's supposed to be booted to find the message saying that 'startup repair' is attempting to repair my computer, then it gives me a window giving me the restore point option and so far it always fixes the problem. I'm not even sure what would happen if I said 'no' to that option, but the computer wouldn't start, I'm sure.
My computer takes a long time to boot up and I don't want to sit there every day for weeks waiting to see if the problem will happen again, but even if I did catch it having the problem I don't know if it actually gives me the option of going into safe more before it starts 'start up repair.' (I'm guessing that it doesn't since it goes into startup repair by itself, but I dont' really know) If it did I could do the uninstall of Avast by your directions and then try to reboot my computer in normal mode and see if Avast was the problem???
I don't know much about computers and I get confused easily, as you see. For instance when you talked about doing a 'memory dump' I have no idea what that is.
thanks again