I have Excel 2007 on a Vista-64 platform. A set of updates came out
recently, after which every time I try to save a spreadsheet I get the
message "Excel has stopped working and must shut down". When it restarts,
Excel says the autorecovery version of my spreadsheet is not a valid Excel
format, and I lose all my work. I did a system restore to prior to the
updates which temporarily fixed the problem, but it came back with the next
automatic update install.

Solutions? (preferably one that doesn't involve turning off updates entirely)