Time Machine is stuck on "cleaning up" and now Finder is "not responding"

I started a TM backup of my La Cie 650GB external drive last night - this morning TM says it's "cleaning up" and hasn't moved from 163.41 GB of 209.69 GB - likely it's been there for hours since it's been an hour already and it hasn't budged. This is my first backup in about a year (yes, I know, but time gets away from me...). I searched the forums and web for help, but nothing is comprehensible (like Pondini), other stuff is too arcane for me. Some people talked about deleting files that say ".inprogress" but don't say how to find those files, and others warn against that tactic anyway.

But now Finder is "not responding" and I'm afraid to Force Quit Finder - how would I do anything then? I tried turning off the backup on the TM interface, but all it says is "stopping backup" without actually stopping. I can't quit it by clicking the x at the end of the progress bar (which is a barber pole) because Finder isn't responding. Now the TM progress bar has disappeared and so has the TM interface - maybe because I clicked "stop backup", but the La Cie icon on my desktop is still green, indicating the backup is still in progress (I think). I can't access any apps because of the inoperative Finder, though I can access the web. I'm about to do a power-button shut-down but thought I'd ask here first. Other posts here have said TM is handled in OS X forums, while below I'm given the choice of TM and OS X forums, so I'm choosing both. Thanks all.