Thanks for taking a look. I noticed the same message that you got, but I had no idea of what to look for. Your comment triggered me to look in the database for the ID of the plugin and I found that there is no plugin with that ID number (529).

I'm not a programmer, but it looks to me as if plugin IDs are loaded into an array within plugin.class.php and when the function call runs, it cycles through the plugin id's until it hits #529 - can't find it and chokes. My question is where are the plugin id's found that are loaded into the array? Maybe that is the source of the error?

I also have a mirror site I use to test updates and on this site I turned off all CB plugins except Core, languages and Paid Subs. The problem still exists.

I'll do a fresh install on my local server and test as you suggest.

I appreciate your help.

[Update - partially solved]

Sorry for my long absence - my attention has been focused on finding a resolution to this problem. In thinking this through, I realized the problem was either a script error somewhere or in a template, since it only affected one browser. That is exactly where I found the culprit.

The issue with the registration page disappearing was apparently caused by IE8 misinterpreting a line of code intended for Firefox. I found it in the CB Dark template.css file in the .cb_comp_outer { } statement that was changed 7 months ago in modifying the site template to display rounded corners and a gradient background. This was never a problem until now.

The code is: -moz-border-radius: 7px; /* FF1+ */. I simply commented out this line and the form is now displaying. "Simply", yeah right. I hate to even estimate how many hours I've spent on this.

Note to anyone following this thread; you will not find this code in your template as it is specific to my site only.

What is unanswered is why did this present itself in IE8 only after the upgrade to CB 1.7 and why is IE8 interpreting code intended for Firefox? Those are really rhetorical questions.

Still remaining unsolved is the error message that is popping up in both the front end registration screen and in User Management that was the initial subject of this thread. And a newly discovered issue with IE8 that only one of the drop-down menu items in the main menu bar on this same registration screen is not displaying. But, that's going to have to wait until I feel like tackling it.

Kyle, thank you for sticking with me on this and guiding me to a final resolution. Your help is really appreciated!