Hi,
I have exactly the same problem. Nowhere can I find any solution. I had some geometry problems with my feature class, but even after fixing that, it still happened. Today I have enabled caching for my layer, and it seems to work. It still happened, but much less often; in the three hours after enabling caching it has only locked up once, and also it's crashed once. Maybe that doesn't sound that good, but when it locks up on you every 5 minutes, it's really something.
I noticed in my task manager (the famous ctr alt del) that the cache manager kept running even when I exit ArcGIS; that's how I came up with the guess it could be something to do with caching. It might be worth a try. Also some program called AppROT EXE keeps running after closing ArcMAP. ArcGIS Connection also doesn't properly exit after closing ArcMAP. It annoys me 'cause I like stuff to behave neatly. Maybe it causes some of the problems.
I notice that when I'm very careful and do not edit many features at the same time, and be sure selections are cleared before saving, and wait patiently for one small thing to finish (for example just selecting one feature) before doing something else (enter an new attribute), the program locks up less often. But it doesn't only lock up. Sometimes it just all crashes on me. Yesterday I have sent like twenty error reports.
Normally I don't reply or post on internet but knowing it really can drive you mad not to mention all the work you can lose (I now save after every edit, annoying but not so annoying as to lose it all) I decided to pop this in. Hope it helps.
Good luck and keep saving.
P.S. I use stand alone ArcGIS basic license only so it couldn't be server related. I have ESRI ArcMAP 10.1 and recently installed service pack 1 for Desktop.
I work on an existing feature class (file geodatabase), I only adjust attributes and some merging/splitting the features (they are polygons). Very simple work, shouldn't give any problems, right? A very simple feature class too. No joins/relates, no nothing. Some of the attributes are using a domain, the rest is all simple text or numbers.
-EDIT- These four things seem to have done it for me;
1. Do not enable ArcGIS connection
2. Enable caching: Layers properties, auto cache.
3. Check geometry and fix when there are problems (these tools you can find in the toolbox)
4. Work slowly and carefully, maybe not the fastest way to work but it works. And you work carefully, so less mistakes (at least that's my thoughts). Be careful not to have too many features selected and don't edit a whole load of features at once.
Can't promiss anything but it might take away a lot of irritation!