I logout yesterday to a 100% fine webpage and login this morning to find this:


These screens show the left 1/3rd of the webpage. The right hand 2/3rds are blank. I have one other webforum I visit doing the same as this, all my other links are okay. YouTube is the same whether I'm logged into my account or not.
Mozilla Firefox 17.0.1 Windows 7
In this state YouTube doesn't work at all, doesn't play any videos, etc.
What I did do last night was run free Avira System Speedup which cleans out junk files, temp files, broken registry links and defrags, but I have run it numerous times before without any damage or anything weird happening.
Also to my horror I found out just now I no longer have any system restore points on the PC whereas in the past I had several. It looks like the Avira software removed those without asking me!
I have a laptop with the same favourites/bookmarks configured on. I could use that to bring that file across, though not sure if it'll work.
Anyone got any ideas?