When I first met up with the Homepage module, I realized that dialog-class.tcl had to go. So I set about excising it from the code. I still have the tarball -- although it's the ClassicACS, so you'd have to port it to OpenACS.
Basically, Usman decided that all errors and system communications should take place on the same page. To wit, dialog-class.tcl. So, every time you do something that the homepage module doesn't like, it sends you to this thing that looks an awful lot like a Windows Dialog Box TM.
I'm not sure which error you're running into, for the simple reason that _all_ errors get caught and masked by this dialog-class.tcl. And, apparently, this is a relatively non-descript error message.
I personally feel that the only way to use the homepage module is to excise the dialog-class.tcl file (and all references to it) from the entire thing, and to throw errors straight from the page. Maybe by using regular error pages like the rest of the ACS (Open or Classic) uses...
My $0.02
