Problem with a url containing ampersand

Since I upgraded my blog from WP 2.0.3 to WP 2.1 (now 2.1.1) I mentioned that one of my posts containing an image which is hosted on box.net storage service (actually posted using its post to blog feature) is displayed larger than before (to be honest I restored a backup before completing my wordpress upgrade).
Problem goes here: my post image address is:
https://www.box.net/index.php?rm=box_v2_download_shared_file&file_id=f_38997162&resize=1&width=400
but after upgrading (or may be restoring my backup) its ampersands were replaced by a ” & a m p ; ” thing. I tried to replace them manually but after doing that url goes in post like this:
https://www.box.net/index.php?rm=box_v2_download_shared_file & # 3 8 ; file_id=f_38997162 & # 3 8 ; resize=1 & # 3 8 ; width=400 (I added some spaces to highlight what bothers me)
I solved my problem temporarily using a “style=’width:400′” statement. However I want to know is this a WP2.1 bug and how could I prevent this from happenning again.
This is my blog post url:
https://www.gozir.com/1385/11/01/photoshop-custom-shape/ (Persian)
Thanks!