Malfunctioning hardware can cause system instability which may be mistaken for software bugs.
Faulty RAM
Faulty RAM can mimic both software and hardware problems. Both the live and installed versions of Ubuntu provide an easy way to test your ram by running memtest86. Memtest86 is run by selecting the GRUB menu when booting the computer and selecting the memtest entry. Memtest86 will perform many different tests on your ram, some of which can take longer than 30 minutes. To throughly test your ram, let memtest86 run overnight.
Before trying to solve any computer anomaly, it is a good idea to ensure that the ram is not faulty.
Failing disk
A failing disk can cause computer crashes.
Self-Monitoring, Analysis and Reporting Technology System (S.M.A.R.T.) is built into most modern ATA and SCSI hard disks. To use SMART to check your disk, install the smartmontools package.
To all information provided by SMART on /dev/sda, run
sudo smartctl -a /dev/sda
To run a selftest on /dev/sda, run
sudo smartctl -t long /dev/sda
To view the results of the test, display all information (see above) or simply run
sudo smartctl -l selftest /dev/sda
An alternative way to check your disk is to use badblocks. To perform a non-destructive scan of the disk surface, boot the live cd and run badblocks from the command-line
sudo badblocks -nvs /dev/sda (where sda is the disk to examine)
To recover data from a failed disk, see DataRecovery.
Temperature
The lm-sensors package can provide you with temperature and fan readings from your motherboard. Alternatively, you can view your hardware temperature and fan values from your BIOS menus.
CPUBurn
CPUburn is a collection of programs to put heavy stress on CPU. These programs are designed to load x86 CPUs as heavily as possible for the purposes of system testing.
Warning: The goal has been to maximize heat production from the CPU, putting stress on the CPU itself, cooling system, motherboard. This may cause data loss (filesystem corruption) and possibly permanent damage to electronic components. Use at your own risk.
http://packages.ubuntu.com/search?keywords=cpuburn&searchon=names&suite=all§ion=all
for an Intel processor, run
sudo burnP6
For AMD, run
sudo burnK7