I see now you said you had a mouse freeze, meaning you can’t move the mouse at all right? Is this happening every time? Often that indicates a hardware-level issue and Macsbug might not work. (In that case, almost nothing will work really ... ). I had similar issues to what you describe with a Turbo040 installed in one of my SE/30s in the past, never could figure it out entirely — seemed to be heat related (after a while the thing would run hot, and issues would occur randomly).
But yes to activate Macsbug you should just be able to hit the interrupt switch, assuming one is installed. If Macsbug isn’t installed, that should bring up MicroBug. Either way, if nothing happens, the Mac is past the point of diagnosis and must be reset.
If you CAN get Macsbug up, the next question will be to see what chunk of code is running at the time of the crash. “WH PC” may tell you, or if not do a stack crawl with “SC6”. The Macsbug reference linked above describes these commands - I actually think it’s one of the best Apple technical docs of the time, with great examples and even a basic overview of 68k assembly, but it does require patience to learn.
Be sure to read all eight chapters and the five or six appendices! If that doesn't make the sweat pop on your forehead, nothing will.
Alright, today was the delivery day.
Pismo - Powerbook 400MHz/1MB Cache/64MB/6GB HD/8MB Video/DVD
Bad news first. The Pismo didn't come with a charger and my 12" Powerbook G4 charger doesn't fit there. Also missing the cover for back side connectors. Looks somewhat rough outside but keyboard and screen seem to be fine.
iMac - Starts up, has OS X installation and 9.2. Booted to OS X first fine but then booting to 9.2 hangs at the desktop after complaining about bad date. I think I'll try get rid of this asap, takes way too much space
Beige - PowerPC G3 300MHz 1MB Cache, CD and ZIP-drive. After vacuuming, removing three coins and a stuck disk from the floppy drive and replacing battery it booted up fine. No leaks from the battery or capacitors. Mac OS 9.2 with bunch of graphic design software. Memory has been upgraded to 320MB and it has USB and FW cards. The original 6GB HD id still inside and working. I think the floppy drive might be broken or at least requires good cleanup. I have to study a bit how to deal with this type of a disk drive.
Yeah, it ... takes more fiddling-with than a PC-focussed scaler, but the results seem pretty nice. I've been using it with my Q950's onboard video and it's been rock-solid. The only thing I've had issues with with it so far are some of the weird older modes on my Acorns that are very low-resolution and have other weird and TV-like characteristics. The documentation does have a table of PC modes and suggested settings for them, which is a good starting point.