I just experienced my first lock-up: pasting some data on a spreadheet, I needed to use "Text to Columns". I highlighted the cells then click on Data -> Text to Columns..then the spreadheet froze :(
I waited for about 3 mins then decided to use "Reset Crossover" function.
After a bit, it tells me that all CrossOver finctions have been stopped. I re-started Excel and it greeted me with the recovery pane. I chose the spreadsheet I was editing and started where I left off. Kudos to the CrossOver team (and the Wine team!) for making Excell really think that its in a Windows enviornment. Kudow too to MS for making this functionality.