Don't mention it. I'm glad to hear that the issue was solved by getting the dust out. Usually if the tricks mentioned above proves no effect, i start to take backups of the most important files, and get ready to wipe the whole system clean and do a fresh install.

I used to do dust cleaning monthly, until i upgraded to watercooling. I still do regular maintenance every 6 months or so, but it's mainly related to changing the water and seeing there's no signs of corrososion or leaks. After that i just take an pressurized can of air and gently blow the interiors clean.

It's funny how i sometimes get some weird looks when i tell someone to clean out their PC's interiors, especially if they have pets, as they seem sceptical that'd be the issue. But, i guess times change, and the proper cooling seems to be a major issue these days.