Dust is not good.  Kalle is correct.  Inside electronics it reduces the efficiency of heat sinks and things.  I have found a very nice blower device that is ideal for cleaning out computers.  It is slower than a compressor but way fast enough to remove dust effectively.  I do that outside on my driveway in the day.  You can see everything well.  Good to check how everything is seated and connected inside too.  Does not hurt to disconnect and reconnect everything either.
 
I have got three desktop towers and it still surprises me how much dust comes out after 3 or 4 months even.  (mainly the office machine. Interesting that the studio computers where I am much more anal about dust are much cleaner inside too)
 
Another bad thing about dust is when it gets into sliders/faders and pots. It can effect crackle/noise into the signal chain.  It pays to keep a studio or any situation where mixers are present clean and dust free most of the time.  Those mini vacuum tools that attach to the end of a normal hose are great for getting into mixers which can be difficult to clean under normal conditions.
 
I use a vacuum with a soft brush and just go over the whole room at least weekly.  And then the mini tools for the mixers and things.  So no dust settles for long.  Some never clean the dust away and it builds up causing problems with sliders and noise etc.. I have never had an issue with a noisy control anywhere in the analog signal chain in 35 years of studio operation.  Everything looks pretty too if clients come in.  And for you too making you feel better in a clean environment.
 
I have got a Roland JD800 synth with all those sliders on the front panel making editing synth sounds a dream.  It does not like being dusty either.  Parameters jump around at random as I move sliders if I let it get too dusty.  Dust can manifest itself into our world of electronics and audio in many ways.  
 
The ultimate way to keep it out is to get one of those positive pressure devices that raises your studio air pressure slightly thereby forcing the dust out of the room and never lets it get in.

Crazy dust here in NYC. Despite having an $800 air cleaner with 3 stages of filtration, I still fight a constant battle with it. I wonder if much of it is still 9/11 dust. Anyway it's definitely about time I vacuumed my DAW.

Thanks for all of the ideas and thoughts. Going to try some different things.

Dust... the bane of modern electronics.
 
No matter how clean you keep your studio space, dust is inevitable. 
 
Check the air input filter from time to time. When you see it starting to turn gray, it's time to clean the machine.
 
Open it if it's a desktop.  I use the air in a can which is moisture free. I also use a clean, dry paint brush to get into and between the cooling fins and down on the circuit boards. It's amazing how much dust can get on the boards as well as in the cooling fins. All of it needs to go.  
 
Blow it off first, brush it next, blow it off again.....
 
Blow it out. Brush it out.... just get it gone. The processors create a lot of heat and those fins need to be clean.
 
I went to a service call for a company I do some subcontracting for. It was in a hospital maternity ward's security monitoring system. You would think, that of all places, that a hospital maternity care ward would be a clean environment. You'd be wrong.  The servers were crashing after they were on for an hour. I looked at the input ports for the server cooling air and it looked like they had cotton stuffed in them.  Some canned air blown on the port resulted in dust bunnies in the air.  I opened the servers and the processor heat sinks were a mess. There were dust bunnies all over that desk when I finished. but the fins were clear. Needless to say, the head of maint/security didn't want to hear that the only problem was a lack of preventative maintenance in cleaning the dust or that the crashing they experienced was that simple to fix. I have run into this very same issue in several other hospitals as well. BTW: the first one I mentioned...the servers were only 9 months on the job and in that time were totally clogged. I suggested to the maint staff that they schedule a dust cleaning on the system every 3 months to prevent this issue in the future.
 
The ones I love are the ones where I'm there for something else, and I look at the server and the USB port on the front has a dust streamer and fuzz around it where the dust exiting the box has built up. If it's on the USB port, you can rest assured the inside is wrapped up with it. I'll usually blow it off with canned air and inform the staff to clean it more fully.....which I'm 99.9% sure will never happen..... In the words of Arnold.... "I'll be back"
 
At home, in the studio and house, I check and clean my studio electronics periodically to keep things running cool and smoothly.