I don't see that dll on any of my Win7 systems with the 12.1 client. Carl Webster Consultant and Citrix Technology Professional <http://dabcc.com/Webster> http://dabcc.com/Webster From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Jan Subject: [THIN] Re: Error message Thanks for looking. It is the web-plugin. On Wed, May 11, 2011 at 3:17 PM, Raffensberger, Stephen D <sraffens@xxxxxxxxxxx> wrote: Hi Jan, I can't find that file on my client. I'm using the on-line plugin 12.1. Are you using the on-line plugin or the web plugin? _____ From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Jan Subject: [THIN] Error message Hi all, I have a site that has several PC's getting an unhandled exception on "esc5cui.dll". I can't find anything about this file on the internet. However, it is identified in the error message as being part of the Citrix 12.1 client.