To start: I have a toshiba satellite 1400-s151 laptop which is 2-3 years old. I have window xp home edition. It never gave me a problem like this...UNTIL NOW. It all started with this blue screen is:

Kernel_data_inpage_error

Then it says if it is the first time the this happens restart your computer

It also says that it could be due to bad installation of hardware and/or software. Ways to fix his is to disable Bios memory options such as caching or shadowing.
oxoooooo7a (0xc0201850, 0xc000000e, 0c042f3860, 0x80614cbb)
The after that it says Dumping Physical Memory.
and underneath that is says something like(didn't quite catch it sorry: atapi-sys-address F9788CA8 base at f9779000 datestamp....(didn't get the last part of the last line sorry

then it will restart and it will recover (after dumping physcial memory) and windows error report screen will show up and will say:
windows has recovered from serious error (on error report it will say: error signature: BCCode: 7a, BCP1:Co20B1850, BCP2: C000000E, BCP3:80614CBB, BCP4: 0D7A6860
OS ver:5_1_2600
SP:-2-0 Product:256-1
on error report contents from tech info click here:
-the following 2 files will be included in error report:
1. drive c:\Docume~1/Nabeel(user name)\LOCALS~\Temp\wer484.dir00/Mini06305-01.dmp
2. drive c:\Docume~1/Nabeel(user name)\LOCALS~\Temp\wer484.dir00/sysdata.xml

That was just the first time. After a couple of days it got worse by doing a couple of times more and showed me another error which is (not as often as the first):
Kernel_Stack_Input_error
same thing as the first error except it says now:
0X00000077 (0XC000000E, 0XC000000E, 0X0000000, 0X099FD000)

And then after that it said this one time also on a black screen:
PXE-E61: Media test failure, check cable


After that, it just keep showing the black screen (pxe-361) over and over again and makes a noticeably loud click noise never heard before (not link clicking on a link).

I pinpoint the problem why did it all happened and I came down with 4 things (its only these anyway):
1. my first and main suspicion the whole thing started is when my the free download manger encountered a damn BUG. I uninstalled the program but it didn't help (also erased its registry history with regcleaner and tweakregcleaner)
2. I acidently set my externel hard drive one volume (have 3 volume in the external HD) as active (from computer mangement, storage, disk management snap-in, but i dont think that is the problem because i had it active for about a month and during that time it never gave me an error or any of that kind... (again until the download manger encountered a bug but not the problem with the hd just the error)
3. I downloaded 300 files (about 20 mb each) in less then 8 days (i was on trial so during that time i want to downloaded as much as i can so i won't get fully billed ) and it was the first time in those 8 days i used my laptop 16 hours a day. However, again i also don't think thats the problem because i scanned all the files with the virus many times and spyware (the site also has a strict policy on spyware so they couldn't and din't have any, for that i am sure)

4. Also, one more thing i just remembered now which is i scanned-only with a registry cleaner called repair registry pro and it found a lot of problems (more then 300 mostly file/path reference). therefore, should i buy it to fix it (is it important to do that? is this be the cause of the kernel message errors i am having?) or i should buy another registry cleaner that is better then this one (which one do u think i should get or should i get the one that finds the most problem in my computer?)

MY REQUEST to all of you is: Can you please tell me how to fix the bug (if thatís what making the error screen show up) by what program that does it and how to undo the external hard drive volume as unactive because i don't use it all the time (just to backup files) and just turn it off when i am done. Or what do u suggest I do (excluding virus, spyware check done that already)