I purchased a generic battery for my Sony laptop this week. However, when I installed it in my computer it would not work. An error message popped up saying my computer was going to sleep and that the battery may be incompatible.
Customer support pointed me at the following web site: http://forum.notebookreview.com/showthread.php?t=20440, which points out that Sony laptops are running a little software program called ISBMgr.exe that generates this error when you insert a generic battery. It appears to be the only purpose of the software, and if you disable the software the genereic battery works fine.
I paid about $100 for my battery, where a Sony brand equivalent would have cost $370.
Sony is really exploiting its customers here.