Access violation in quick reports


I have the following strange problem with quick reports. Sometimes when I
close the quickreport preview I get the following error mention: "Access
violation at address 00499F68 in module InvPro1.exe. read of address

Does someone know the cause of the error and how I can remedy this error

By the way: sometimes I get very strange errors I the reports

Problem occurs on win 95 en W2K maybe also on another Oses. Bat I don't have
test this. I use Delphi 5 with update pack 1.

Thanks in advance.