Urgent help.! Many Symptoms

Computer is going weird.
XP SP3
It boots up really slow, and when you do simple combo commands like clicking the two buttons of the mouse consecutively, it takes long for the computer to react.
When it starts up, I can hear the logon sound, but I can't play any sounds, it says that I have a hardware error in my sound card.

I also can't print- it says that the printer is not connected or that there is a hardware error.
When I try to maintain it, it says that defragmenting has been disabled.

I also can't edit the Registry because it says that I don't have admin privileges when my account has administrator privileges. I also can't do system restore because of not having admin privs. When I start up, I sometimes run EndItAll but Only Enditall is displayed on the window. When I go to the task manager "Tuneup Utilities", it doesn't list any programs or running files.

I just recently installed Garena client and Call of Duty 5: World at War patch 1.2. I also can't run the internet-a 3G modem which I reinstalled because the computer "cannot recognise the device" or it cannot connect. Up to now, it still can't connect and I am using a laptop with the same modem to type this. Help Please! T.T.....

 

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just a question... but do you know how to format a computer mate?

because the problems your giving make it seem like to me - that a whole host of things have gone wrong, and even if u pinpoint them all and 'fix' them you'll encounter errors in the future, id suggest (if you can) formatting, and i mean completely - as in, erase everything and reinstall a fresh OS (windows XP or similar) and start again, then if u still experience problems - its hardware related.

it may just be my personal opinion - but 2 hours formatting is better then a week of testing and poking