What version of MultiIE are you trying to install???
If you check out this web site:
http://www.southwaycorp.net/
You'll see the following message:
"Special Note: The latest build of MultiIE now supports Ipaq 41xx / Toshiba e80x and all other Pocket PC devices! For best results before you install the new version, please uninstall any old version of MultiIE and soft-reset your PDA. "
This, of course, implies that previous versions did not support the iPAQ 41xx models. Try downloading the latest version - but, just to be safe, do another backup before you install it.