uddeIM redirects to a valid page, usually the inbox.
The problem is that the itemid is sometimes not valid. On Joomla 1.0 and older Joomla 1.5 versions it was possible not to pass the itemid and Joomla redirected to the correct page. On current versions this is much more restrictive and requires always a valid itemid. When the user has more then one link installed or uses an unpublished link (this was also a work around on earlier versions) the router.php error occurs.
A common problem is:
Redirecting from a module to a component. This requires that the module tries to get the components itemid. When more that two menu links exist, the module may get the wrong one.
uddeIM FAQ contains several ideas how to fix this problem. Usually _one_ valid menu link fixes the bug. Sometimes it requires to "overwrite" the itemid manually (thats why I have added this option to uddeIM).
uddeIM & uddePF Development
CB Language Workgroup
CB 3rd Party Developer
