Hi, I'm a new member to the forums but used to lurk for a while; found all the answers to my problems just by doing that I don't seem to be able to find an answer now, so I hope to get one by posting...

Often when I boot up my pc the thing emits a noise similar to the noise a dot matrix printer makes while printing. When I hear that noise, I know I'm screwed, for afterwards it displays "Operating System Not Found" on the screen and it goes no further. I used to get the problem every once in a blue moon but now it's happening on a daily basis and it's really aggravating. The way I usually fix it is by opening the case, and unplugging/replugging everything from the HD to the mobo. Now I'm too lazy to do that every day so I just shake the case a little and it eventually works I'm running out of compressed air to spray and my patience with this problem is definitely at an end So far I can estimate that the HD is probably not the problem, as it's still got everything it should have on it, I'm hoping it's just a fault connection... Any help would be much appreciated. Thank you

Is it the same sound as when you click on the floppy drive when theres no disk in it? If it isthe floppy disk controller may be on the way out. Have you run scandisk with a surface scan to be sure the hd is ok?
Only other thing you can do is try to isolate the problem. Next time it does it, take off the case and just replug the hd in and try rebooting with the cover off. Work your way through each connection till it boots and that should show which one is the problem. If necessary, buy a new ribbon cable for the suspect one.