Hi
There seems to be several different issues.
1 the AccessPoints reloads.
2 the users loose contact with a server.
First you do is check the logfiles.
If you do not have any logfiles you start with downloading a syslog server (fx kiwi syslog daemon) or any other that suits your taste
set up logging on both the Acesspoints and the switch.
Now you will se what they think are happening and most likely they will tell you what the problem is, quite straight forward.
if they do not, then start keep track of times and how the faliures seem to happen.
check for dumpfiles to make shure one of the problem is not that the switch has a problem and fx reloads and so on.
this will give you a good start.
Good luck
HTH