Try setting up a new account & see if you have the same problems.

As for your main account FW, try temporarily removing all your shared files to a new location (ie: FW will then be sharing zero files unless you have partial file sharing turned on). This will at least help reduce 'some' of the load on FW & hopefully enough to at least access the download window.

Also make sure your Java is up to date.

There are other ways of reducing some load on your FW, but would need to be able to access the FW preference options.