That sounds like it could be the standard Windows "Loading Image" dialog
box. And if so, then you certainly should turn it off - it may actually
cause Access to crash while processing the report.
You need to modify some registry keys to prevent this. The details are
available at
http://www.mvps.org/access/api/api0038.htm, and a full list of
all keys to modify is available at
http://www.mvps.org/access/downloads/Set_ShowProgressDialog_To_No.reg (which
is the "registry file" link on that page).
The easy way to incorporate these is this: Cut/paste the entire content of
the registry file page to a text file (I used Notepad), and save as a .reg
file. Then all you need do is double-click the file, or right-click and
choose "Merge", to merge the entries into your registry. For a 19kb file
of entries, that's certainly faster than entering them all manually ;-)
Note: there are more entries here than are actually needed to solve the
problem, but it's so easy to import the lot that it's not worth figuring out
exactly which ones you need (and, in my case, at one time some of the others
had been corrupted and I had a very weird problem - re-importing all the
keys cured it).
HTH,
Rob