Please help! Major and odd mini problems

Question

I really am begging here. Traditionally a pc/windows girl (out of sheer ignorance only) I bought my mini in November 05. Have had problems with it since day one but assumed they were of my own creation due to pc/mac switch. Over time, the problems that were on my end have largely disappeared while others worsened. Because the remainder are inconsistent, I have been unable to get proper diagnosis from repair people as 1) unit usually doesn't act up in their presence, and 2) obvious issues seem to have been ruled out. I am pretty much at my wits end and about to throw in the perverbial towel. After reading through some of the excellent suggestions you brilliant folks have graciously given others before me, I thought i'd run this past you...
mini is set up to access cable internet wirelessly through airport extreme. Mini is in bedroom about 15 feet from airport. Airport is in livingroom with remainder of media setup. Mini sits flat onmy hardtop desk with nothing on top of it.
Original and main issues surrounded the monitor ( 14" Flatscreen ProView 468) intermittently cutting off for a few seconds/ minutes and cutting back on, programs not seeming to operate the way they should, trouble opening files and programs, etc. and most importantly, a consistently slow internet connection taht often simply dropped out altogether for brief and also extended periods.
I thought the internet connectivity issue was the cable company's fault but have recently borrowed friends powerbook and it experiences no issues at all.
As well, have replaced cable modem, ethernet cable etc to no avail. Signal strength according to cable co. is top notch. A friend recently gave me a new larger monitor (17" flat screen hp pavilion f1703) and once connected I noticed that most of my system issues seemed to disappear. The monitor stopped shutting off, the internet connection was consistent and oh-so-fast, and programs were responsive and functional. I googled a bit to discover that some folks have had monitor incompatibility problems with the mini. I began to feel I was amidst a breakthrough- until about a week later I lost internet capabilities altogether. Ruled out it being a cable company or airport extreme issue as the aforementioned powerbook was able to access network and go online as normal.
When the internet connection is unavailable, the diagnostics would show connection to the airport and that I was online via the airport - yet indicated a server failure. I moved the mini into the same room with the airport to rule out interference and signal issues and still no internet. A mac tech came to my house and of course, the moment he turned on the unit, it coonected to the net just fine. When he left, it went back to it's previous behavior except that the connection was intermittent as opposed to always gone.. While here, he checked to make sure I didn't need to do certain cleanup tasks, etc. and noted I have plenty of power and memory available. He suggested I order Norton Utilities for Mac a d see if running it from disk would help.
I googled again to learn that Norton Utilities might not be necessary and also might not be good for this os. Problems persisted and even went so far as system not recognizing airport at all, out of range indicators, etc. So, after further reading I decided to change my network settings from open to WPA-personal as some suggested this could cause probs for mini and also reset pmu. immediately, my internet connection returned, airport network fully recognized and has been consistent for the last 24 + hours. Big cautious sigh of relief except now as i write this, the monitor has begun it's intermittent turn-off again and my airport status indicator shows no signal. UGGGHHHH!!!!
IF this is a hardware issue, will the hardware test disk always indicate such? I will run tonight. Any other thoughts or suggestions that don't involve a 20 story building? Thanks in advance...

Answer 1

Thanks again. I did archive and install today. Haven't used the mini enough since to know whether problem is resolved. A friend suggested I reformat the drive after making sure all is backed up. I assume this is the same as erase and install? In the interest of being thorough and eliminating possibilities I thought I'd do that before taking to apple repair. Problem is they didn't find anything before. I can't tell u guys how much I appreciate the responses!