I don't have any problems myself, but reading the questions from Support which nonnux pasted did raise some questions of my own:
From: nonnux white
How much space do you have left on your C: drive?
If the point here is to ascertain that disk space hasn't run out, it should say so. It should also mention why it's writing to C: when SL might have been installed somewhere else. Or if a minimum amount of free space is required on C: as well as in the installation directory, then it should say so, and why, and how much.
From: someone
Also when was the last time you went to c:\Documents and Settings\(yourusername)\Local Settings and deleted the contents of your Temp Folder?
What for? That's not an SL directory, being told to delete its contents might well cause total havoc and mayhem to other applications.
From: someone
I would also suggest going to: c:\Documents and Settings\(yourusername)\Application Data\Second Life and deleteing the contents of your Temp folder.
Well, at least that one does belong to SL ... but why should you have to do this manually, and what does deleting it actually achieve? (General point: I want to be told why I'm doing things, not follow instructions blindly.) Perhaps Support is guessing that something in this SL directory is corrupted, and therefore that deleting it might provide a solution. If so, say so. Don't treat customers as dummies.
And does this still apply if I've installed SL in (say) D:\SecondLife or some other place? And if it does still apply, why is data being written to somewhere other than the specified installation directory? (You have to follow the user's installation requirements --- she may have installed in D: etc precisely because there is no room in C:.)
From: someone
Finally, when was the last time you defragmented your hard drive?
Defragmenting your hard drive merely speeds up access to files.
Maybe I've misunderstood. Was that a completely general response to unspecified client problems, especially lag? It's hard to see how any of these sentences apart from quote #3 address client crashing.