This is what the VFP Help says:
Cannot access the selected table (Error 1152)
You have attempted to select a table outside the 32K work area range or are attempting to reference a file variable in a table that is not open.

For the ‘attempting to reference a file...’ part, I see two situations:
1. Your code or objects refer a table that is not (or no longer) open – this happened to me.
2. Your code or your objects refer something that VFP thinks is a table – never happened to me, but I guess that specifying a non existing property of an object aObj.aProp might look like aTable.aField...

Now you have a ‘complete’ list of causes, all you need is to look at your application ;-)
Usually, what varies the most is not the cause of the error, but the circumstances, i.e. the applications that we develop. You don’t provide any details, and I’m actually pretty sure that if you provided an adequate description, you would have almost found the problem.