Weird Crashes - Any thoughts?

Question

So, the quick review of my past few weeks:
1. Purchase MacBook Pro (late 2007 non-glossy) 2.53 Ghz 24.11.2008
2. Two minutes out of the box, was dealing with annoying noise coming from HD, like a squeaking, turning gurgling noise every 30 seconds or so.
3. Went back to the store and said "I didn't want a machine that talks to me"
4. Store says o.k. and replaces my Toshiba HD for a Samsung HD (assuming Tosh. was 7200 and Samsung is 5400)
5. When I get home, annoying noise is gone! Awesome! Now I cannot open iTunes or Front Row without MAJOR lags in my system. And I mean M.A.J.O.R.
6. Read up on problem and figure that I need to format the new Samsung HD so it knows what the fakk is going on inside the computer. So, I run an "Archive and Install"
7. Beautiful! iTunes and Front Row are AWESOME ... BUT, and there is always a but ... now computer crashes. For no reason. At any time. Even with only Safari open. But weird crashes .... example: I was Skyping with my buddy this evening. Computer stopped. EVERYTHING but Skype. No mouse, no functions ... nothing. But Skype was working. Shut down. Restart. Cool ... 5 minutes later ... BOOOOM. Nothing. No response except power button.
Problem again is that, like most Mac owners, I bought the machine to make music / video / photography. It's challenging to have a computer that one doesn't know if is reliable or not. One doesn't want to get 30 minutes into a project and BOOM. Bye bye. And no, one shouldn't always have to be cautious about crashes and constantly be saving their projects. Yes, saving is good, but ALWAYS saving is tedious, time consuming and one shouldn't have to do it all the time after shelling out a few thousand for a machine that "just works".
Any help with N° 7? I am stuck now.
In the car industry they call it a lemon. I think I got the lemon. Twice (I found out they replaced my first one before replacing the HD)
This ***** ... unfortunately, it's also my first Mac purchase.

Answer 1

OK, lets go back to square one and take a look at the things that usually result in slowdowns on macs.
First lets make sure that the drive is correctly formatted and that you aren't suffering from directory corruption of some kins.
Boot up the computer from your Leopard OS DVD, go past the language menu, and then select "Disk Utility" from the "Utilities" menu in the menubar. Highlight your HD (it will probably give the brand of disk and its capacity) in the pane on the left. Now look at the information in the bottom of the window. It will provide various information about the drive ending with something that should read:
S.M.A.R.T. Status : Verified
Partition Map Scheme : GUID Partition Table
If the SMART status isn't verified, or the partition scheme is anything other than "GUID Partition table" then we have a problem.
All OK? If so, then highlight the volume name in the left hand panel, immediately below and slightly offset to the right, from the HD. The usual default for this is "Macintosh HD", though you may have called it something else.
Down below you should now see information about the "Mount Point", etc.
The important information here is the "Format" , which should read "Mac OS Extended (Journaled)" . If it reads anything else then you may have a problem with the drive format.
All still OK? With your HD selected in the left hand pane, make sure the "First Aid" tab is selected in the top right pane of the Disk Utility window. You should see buttons available allowing you to "verify" or "repair" permissions and to "verify" or "repair" the "Disk". Click on the "repair disk" button. This will check and repair and corruption of your HD directories. It will probably take several minutes to run (longer still if it finds problems). If it says that it has undertaken repairs make a note of what they are. If it says that it can't repair the disk, again make a note and post back here. If it says that it couldn't find any problems then we can move on to the next step.
Once the "disk repair" is completed, click on "repair permissions". THis takes some time under Leopard (might even run for twenty minutes or so though it is usually a little quicker than this).
If none of the above indicated any problems then we at least know that your directories etc are in good shape before we move onto the next phase.
Restart your computer normally (ie booted from the internal drive).
Use it normally but start up "Activity Monitor" from the "Utilities" folder. Open the "Activity Monitor" window from its "Windows" menu. Choose "active processes" from the drop down menu near the top of the window. Then click on the "CPU" tab in the lower part of the window.
Watch for any "processes" which are using large amounts of "CPU" (in the "cpu" column. Anything using more than about 50% is unusual. If something is using more than this, take a note of what it is and post back here. Some background programs, and even printer drivers and the like, can be "processor hogs" that consume large amounts of processor time, while doing very little. This can cause serious slowdowns.
Cheers
Rod