For the fast few days I have been having problems with my Mac on its overall reliability. A few days ago I took the back off of my MBP to clean some of the dust, and put it back together. now when I start up I get a bar under the spinning gear that disappears after a few seconds. My start up and shut down have been really slow and often hangs on shut down, when I first installed Snow leopard, every thing was instant. Recently I have been having weird application crashes and problems with installing programs from a DMG (steam). iTunes has given me errors and so has Mail, it just suddenly crashed and asked me to rebuild the messages constantly until a re-boot. I would re-install OS X and use my time machine back ups to restore all of my files but, I think I may be on my last licence of iWork, I went to install it on another mac and it tole me it was invalid, so I am worried of loosing my current licence. Unless that is carried transferred in a Time Machine back up. I use Mobile Internet as my main internet connection, it is all I can get as I am in a rural area, and I have been having problems with it initializing some times and connecting. My ISP is Bell Canada. I would just like some advise on what is going on, when I took the back off I didn't touch anything, and I have done my own hard disk upgrade months ago.