FF "Choose User Profile" Window-can't use FF

I've been using Firefox (primarily) since early December, and this morning is the first time I've seen the window shown in the image attached...which gave me the result shown when I tried to be the default user. I used this site's search feature, and found one similar comment in an old thread. There was no resolution.

I'm here using IE, because I won't answer unexpected questions from software, and I'm not sure what to tell it to get it to work, anyhow. It could be some new bad thing wanting me to give it info. It won't let me be the default user; I wonder who I've been up until now.

When it happened, I was opening a site that uses Sun Java...but didn't get in and have no reason to think there's a connection. Just before, I'd found some of my SpywareBlaster protections disabled, and don't know if that's relevant or not. I'd just run scans and all were clean.

I've got XP Home, SP-1, in a Dell Dimensions 2350 w/ AVG Free, SygatePF, Ad-Aware, Spybot, SpywareBlaster, WinPatrol, IE-SPYAD, Enough is Enough, eDexter, a HOSTS file, and a few days back, added Firefox's AdBocker.

Even if I can use Firefox again after rebooting, I'd be grateful for opinions about what may have happened to change the browser's behaviour, and who I need to be to straighten it out if it happens again.

Also, if I uncheck the box so it doesn't ask, will it do things behind my back, without asking?

 

It took rebooting, but seems alright now. Hmmm. My first Firefox crash...

Thanks, Ron. Have you ever noticed how frequently error messages don't indicate the real problem?

 

Does that happen often when FF hangs up, or was it just a general "it could've been worse" comment that I completely agree with?

 

Phew! That's a relief!