scbs29 wrote:

Literally between switching off at night and restarting next morning I
started having problems booting up. It can take anything up to 5
or 6 tries before I succeed. This has been going on for 4 days.
There have been no changes to software or hardware for at least
3 months.

The problems can be any of :
1. Boot splash screen appears and the pc hangs. Need to switch off
power.
2. The login screen appears and the pc hangs. Need to switch off
power.
3. I log in and get bsod. I have had 3 bsod
IRQL_NOT_LESS_THAN_OR_EQUAL
MEMORY_MANAGEMENT
PFN_LIST_CORRUPT
4. I log in and the pc starts ok. After a period of time of a few
seconds or a few minutes the pc freezes. Need to switch off power.

If none of the above occurs the pc runs normally.

Following information I found on the web I tried chkdsk which
gave a clean bill of health and Win 7 memory checker which
also gave a clean bill of health.

Today I tried quite a few times to startup and eventually received a
message asking if I wanted to try a startup repair. I replied Yes.
I received a dialog stating
Startup Repair cannot repair this computer automatically
Problem signature
Problem event name StartupRepairOffline
Problem signature 01 6.1.7600.16385
Problem signature 02 6.1.7600.16385
Problem signature 03 Unknown
Problem signature 04 1549
Problem signature 05 AutoFailOver
Problem signature 06 1
Problem signature 07 NoRootCause
OS Version 6.1.7600.2.0.0.256.1
Locale ID 1033

The startup diagnosis and repair log showed no errors
except
System files integrity check and repair
Failed Error code 0x2

After this the pc booted up normally.

I have run virus checks with no problems reported.
I have also had some instances on shutdown being informed that it
was an unclean shutdown.
Also told on shutdown that there is a program stopping the
shutdown and to terminate the program before shutting down.
There is never any indication of what the program is.

Can anyone advise me ? Is the next step to boot from the
Windows 7 disk and try Repair installation ?
Should I seek professional advice ?

Packard Bell iXtreme X6620 UK
Intel Core 2 Quad Q8300 @ 2.5GHz
6 GBytes DDR2 RAM
NVIDIA GeForce GTX 750 Ti, 2Gb RAM
Windows 7 Pro, 64-bit
MoBo Packard Bell EG43M
Direct X 11

Disconnect all non-essential hardware from the PSU. For example,
disconnect all USB devices except for mouse and keyboard if those are
USB, disconnect power from the CD/DVD drive, and disconnect all hard
disks except for the one with the OS partition. The idea is to relieve
the PSU of some of its load to see if boot becomes stable. If so, time
to replace the PSU (and of a larger capacity).

Get and run memtest86+ (http://www.memtest.org/).

From online searching on "Packard Bell iXtreme X6620", apparently that
computer model came out around May 2010. That means the CMOS battery is
8 years old ... too old. Replace it. If you have customized the BIOS
settings, note them and reset the BIOS after installing the new battery
and then restore the custom BIOS settings.