Getting random error: "The expression On Change you entered..."

Question

Running Access 2010 on Citrix against a SQL Server 2008R2 backend. Occasionally my users will get an error reading:

The expression On Change you entered as the event property setting produced the following error: Overflow.
* The expression may not result in the name of a macro, the name of a user-defined function, or [Event Procedure].
* There may have been an error evaluating the function, event, or macro.

Once a user gets this error during a session, he will continue to get it until he logs out of the database front end. He can then immediately relaunch the Access front end and go do whatever it was he was attempting to do. The On Change portion will vary in event type (sometimes On Click, sometimes After Update, etc), and it will happen on different forms, but the fix is always to exit the DB then get back in and everything just works fine.

The more I learn, the more I'm starting to believe that it's got something to do with the Citrix enviornment that we're in, but I haven't been able to pin anything down.

I've seen the suggestions to copy the form, and to start with a new DB and import everything. I've done these and it hasn't really helped - i.e. this is random enough that I don't know if the frequency of issues decreased significantly after the change.

• Does anyone have any additional suggestions of what I can do in my Access code?
• Does anyone have any experience with this setup and have some Citrix or SQL Server tweaks that I might be able to pass along? (I don't know if our IT people will listen or try to work with me on it, but it's worth a shot.)

I'm frustrated with the randomness of this, and I hate telling my users there's nothing I can do about it, but at the moment, I'm completely stumped.

Thanks, FreeMan

Edit - Additional details...

• the users are running a compiled .accde
• they are all running from a common .accde file
• this is still happening for a few users to whom I have given their own personal copy to run

Answer 1

The goto fix for random weird stuff happening in Citrix is to disable hooking. Hooks get injected into every process running in a Citrix session, so they could be screwing up something in Access. You can configure registry entries to exclude Access from being hooked:

http://support.citrix.com/article/CTX107825