To reproduce

1. Using fckEditor create a link to a Magnolia page. Save
2. Edit the link and either via source or via link tool try to append ?p1=test to url so it looks like this:
<a href="/demo/page1.html?p1=test">some link with a param</a>
3. Save again. The link is there but the entire query string is gone!

Also the same is true for page anchors. Page anchors do work within the same page but not for the other pages. So

this works:
<a href="#anchor1">go to anchor1 in this same page</a>

this does not:
<a href="/demo/page1.html#anchor1">go to anchor1 in the /demo/page1</a>