FTP to your box and find where the mgcamd file is. It's usually /var/bin or /var/bin/emu.
Unzip any of the versions in this thread and find the mgcamd.ppc file. Extract it to your desktop and rename it to remove the .ppc extention and leave it as mgcamd.
Copy it to the location on the box overwritting the original file and chmod 755.
If it comes up with an error, it's because mgcamd is running, you'll need to stop it first.
Open a telnet session (START > RUN > telnet ip.address.of.box)
Username: root
Password: dreambox
Type...
killall -9 mgcamd
Now copy the new mgcamd file over and chmod 755.
To chmod, that means change the permissions of the file. You need to right click on the file and select attributes or properties or chmod (depends on the ftp client you're using). Check the three execute boxes so that the number changes to 755.
Now, in your telnet session, type...
mgcamd
...and it should start. Or simply restart the dreambox.
That's you...hopefully no more freezing.