Windows 7 system rebooting randomly

Zip the last 3 minidumps and attach the zip file with your next comment. They should be located on C:\Windows\Minidumps

The minidumps you are asking for are not in the C:/Windows directory.

Make sure your system is set to create minidumps, if not change the settings so it does (right click "Computer", select "Properties", "Advanced System Settings", Startup and Recovery "Settings", and then under "System Failure" select "Small memory dump". Here you can also see where they are written to, and change that directory if you want.

Then wait for 3 crashes/reboots, and after that zip the dump files that got created. Also, the directory is usually hidden, so you must make sure you have set hidden files to be visible in your folder options.

First have you ran sfc /scannow yet? to repair any system files tat may be damaged. Has the pc been cleaned by a good antivirus? Have you tested the Hard drive? You can use HDTune on Hiren's BootCD 15.2. If you have a bad block that's the culprit. Check the event viewer look for kernel power failure if that's the case only 3 steps to diagnose in a general way. swap Ram out Ram test sometimes don't show issues with Low voltage combination memory problems try and make sure your ram is all the same. see if it happens again then try swapping power supply inconsistent or overheating power supply will do this.  After that is processor but may consider new pc at that point. These are a few things to try im probably forgetting a lot more.

Ok we'll try all suggestions submitted.

Hardware failure is a common contributing factor.  For example, a common hardware failure is overheating.  Or other common issues involve the power supply failing, the CPU is overheating (the heatsink is clogged with dustbunnies or the thermal paste needs refreshing between the cpu/heatsink), air flow deficiencies that causes the entire box to get too hot, bad memory and/or hard disk failure.

Usually what I do is I go into the BIOS of the machine to see if I can get the CPU temperature if its monitored from there.  Or I can just feel if the case is warm/hot inside.  Then I open the case and use a can of air to blow out the case and clear any/all fans of dust bunnies and boot up again.

These are also some additional starting points to consider when dealing with machine behavior like yours.

Keep us updated!

o/

Most probable cause is a hardware problem such as overheating or bad power supply. If you have another powersupply that you know is working good swap the powersupply and see if the problem reoccurs. If can see a lot of dust inside the case, the system is probably overheating and there by shutting down after it reaches a certain temperature. Check the fans to see if they are turning properly, blow out the dust especially around the cpu, the fans and the vents. Check to see if any capacitors on the motherboard are bulged out or leaking, they should be flat across the top.

without more details - the most probable causes are :
1-bad hardware : PS RAM - DISK - motherboard -video card
2-software: corrupt OS - wrong or damaged drivers
3-overheating  - install speedfan to monitor the temps :  http://www.almico.com/speedfan.php

I'm going to see if we can get the power supply and or Motherboard replaced.

Thanks for all of the advice guys.

I'll keep you posted on what happens.

look also in event viewer for errors - or warnings
no minidmps yet??

No not yet. Having Dell come out to replace the power supply and or Motherboard. They initially wanted us to re-install the OS.

yes - that's something they do not need to do anything for...easy choice

What finally fixed the issue was the motherboard and power supply was replaced.

Thank you all for your help, much appreciated.

no problem - glad to help