Windows Media Player cannot play the DVD because a compatible DVD decoder is not inst

NVIDIA GEFORCE 4MX400
REALTEK AC97 Audio
MICRO-STAR INC. MS-6728
Maxtor 6Y160P0
512MB Realtek RTL8169/8110 Family Gigabit Ethernet NIC
Windows xp service pack 2
Using Magix 2.0 to edit Panasonic camcorder tapes to DVD. For some reason I cannot capture via Magix so I capture via Windows Movie Maker and edit via Magix. Once I have burned the dvd via Magix my dvd player tells me it's a bad disc, my computer get the error message, Windows Media Player cannot play the DVD because a compatible DVD decoder is not installed on your computer, when I try and play it.
I have tried to play other DVD's and I get the same error message. I have re-installed windows media but still get the same message.
I did have Nero installed but un-installed this thinking that it may be causing the problem.
Installed the Windows xp video decoder and am told that the ligos MPEG video decoder impgvd.ax 4.0.0.104 is not compatible.
I know nothing about decoders but have always used window medio before with no problems. I am happy to pay for software that will sort my driver/decoder problems out but would be greatful for some advise.

Go to the site below and download "K-lite Mega Codec Pack v1.34". Its free.
http://www.free-codecs.com/download/K_Lite_Mega_Codec_Pack.htm

Hi There, thanks for your help, I have downloaded K-lite but appear to have another problem.
I was using DVD shrink and it then I noticed that I had no cd rom, I checked the device manager and LITE-ON DVDRW LDW -851S was disabled, I uninstalled and it installed again but it was still disabled with an error message... A driver (service) for this device has been disabled. An alternate driver may be providing this functionality. (Code 32)

Click Troubleshoot to start the troubleshooter for this device.
Troubleshoot brings up a blank page...I am pulling my hair out, all I want to do is make a simple movie from my camcorder, never thought it would be this difficult!!!

hi,
seems that you have problem with the decoder and you need some thing
to fix your computer.
http://support.microsoft.com/default.aspx?scid=kb;en-us;306331
go to this link and take of look donot throuh it.
girish

Go to the site below and download "K-lite Mega Codec Pack v1.34". Its free.
http://www.free-codecs.com/download/K_Lite_Mega_Codec_Pack.htm

i need some herlp as well.. how do you use the k-lite codec pack? because i can't play movies on my media player and it needs that decorder thing..

Since I reinstalled the OS, XP-professional, I cannot play DVDs. I get the "Windows Media Player cannot play the DVD because a compatible DVD decoder is not inst" mesage! help!!