We are using UCanUse UserAttributes v2.9 on recently upgraded v3.3.7 (from v3.2.2).  Since v3.3.7 has the ability to add profile fields, we thought we'd start using those instead of UA's tables; however, we added a couple of fields and now -all of a sudden- none of my users can log in.  They get:

An error has occurred.
An error has occurred.

With this as the URL:  http://ourintranet/Default.aspx?tabid=36&error=Input+string+was+not+in+a+correct+format.&content=0

That's all the information I know.  The fields I added were:

usercode (5 character text)
respcode (5 character text)
location (list)
department (list)
jobtitle (list)
officer (t/f)

Any ideas?  Thanks for any help.

To further what I know.  No portal user account can log in with the error in my OP, but the site administrator account (dnnhost) can.  I've uninstalled UserAttributes completely.  I've deleted an existing user account and recreated it manually with no effect.  I've created a new, non-pre-existing account with no effect.  I verified that aspnet_users, aspnet_profile, and aspnet_membership are all getting populated.

If anyone knows of a module that can move content from one site to another site, I'd probably be willing to start completely over from scratch with a new, clean install of v3.3.7.

I'm pretty much desperate here.

You actually helped more than you know, Mitchel.  While I was setting up my profile the way I wanted it, I removed several of the fields that we don't use here ...like prefix, surname ...timezone and preferredlocale (this is an intranet and we are all in the same zone) ...etc and so forth.  I went through and added all of the default fields back and, through much trial and error, I found that the timezone and preferredlocale were coming in blank for all of my existing users.  So, I set defaults in these fields and, now, all my users can log in again. 

I knew someone would say something that would spark the solution ...no matter how off the wall it seemed.  Thanks for replying, Mitchel.