A few weeks ago, just after I tried to delete the cache and tracking cookies from Firefox (using AVG TuneUp, which seems to have taken more than I asked it to remove), my browser started refusing to load any new sites, or reload inactive tabs, once I had been using it for about five minutes after rebooting it. It also crashes completely when I try to download or upload anything after that point, which is irritating but does mean I have some crash reports to share (bp-5a7c5f6e-0d55-451a-8b2b-15b360250524 is the latest one). I've tried everything I can think of or find on the Internet - Troubleshoot mode, disabling and re-enabling hardware acceleration, refreshing the browser, uninstalling and re-installing it with and without restarting the computer in-between (which seemed to work for a while), culling tabs (although, if I'm reading the crash reports correctly, lack of memory isn't the issue after all; certainly, Chrome doesn't have the same problem even when using more memory than Firefox did), even running diagnostics on my computer's RAM and hard drive - but nothing's fixed it. What might be going on, and how can I solve this problem?