I don't own a Palm but I'll make a couple of suggestions for you to try.
The first is that the Windows User to you are logged on as while install the Palm software has to have administrator rights.
The second is a post I found from the website regarding your error message:
palmUI.dll error message
"I think I've been able to fix my problem. I had made some changes awhile back on the startup menu in msconfig and while there, I had checked "Palm", thinking that it should've been checked when it wasn't. Apparently, that was what caused the problem because unchecking it has eliminated the palmUI.dll error message at startup."
You run msconfig by clicking Start button->Run and typing MSCONFIG and clicking OK
The settings the above user mentions can be found on the Startup tab of msconfig utility.