Reasons why computer starts to freeze

Here is my brainstorm tips why computer start to freeze:

Hard disk drive have bad sectrors.

Windows updates is installing.
Try to stop updates with net stop wuauserv
Disable update with sc config wuauserv start= disabled

Microsoft System Center is auditing you computer
Try to unload with net stop ccmexec
Disable System center service with sc config ccmexec start= disabled

RAM is needs to me more.
Page file starts to increase and HDD is driving crazy.

Page file is turned off.
For example Windows XP with 3Gb RAM and turned off page file sometimes make a interesting half-seconds freezes.

Windows XP is with Fat32 file system.
On my personal experience i can say that defragmented fat32 on windows xp system works much slower than fragmented.

Your antivirus is scanning for files.
HDD is driving crazy.

Hard disk is not defragmented.

If the computers seems to be freezed at startup while on screen is "Running startup scripts" it may be posible that network settings - static ip is setted wrong. Try to unplug you cable and then.. Just to see what happens? :)

If the internet is working but like freezing working, you can restart your modem and router.

If the internet is working, it can be posible that someone use the same MAC address and that means also the same IP address.

If the laptop freezes before operating system starts to load try to unplug batery and ac power.
Plug something in usb port to discharge the system.

You have to many files on hdd. Yeah.
This sound wierd, but if you have like million files on your hdd then better start to clean someting.