Hi Chala .I'm fine.
I will start with I have limited experience with Nero.I do have Nero 6 on my older computer with XP & that is the only version I've used.
I did try to install Nero 6 on my newer computer with Vista.It completed the install but had compatibility problems.I went through the through clean but still had some problems.
Fortunatly for me I had read on the web there might be problems so I had made a backup with Acronis True Image before I did the install so I ended up using that to restore my Vista OS.
Now I will see if I can suggest some things .Some you will have already tried but try them again.
On XP the "run as" for a file when you right click has a selection "The following user:"
Select it.Leave Administrator as the User Name & type in your Administrator password.
Before doing the following if you have a backup software like Acronis you might want to do a backup.
At least get the erunt utility from here & create a registry backup.
You also might see what Nero registration serial number this comes up with if any:
After you download this clean tool:
Try the Nero General Clean Tool from here:
I want you to try these things in Safe Mode.Windows may not let you do all of them in Safe Mode.If not try again in normal mode after you have tried all in Safe Mode.
1. Delete the temp file contents (start run %temp%)
2. Run the Nero General Clean Tool as administrator.
3. In C:\Program Files\ delete the Ahead folder & Nero folder if there is one.
4. In C:\Program Files\Common delete the Ahead folder & Nero folder if there is one.
5. In C:\Documents and Settings\Administrator\Application Data delete the Ahead folder & Nero folder if there is one.
6. In C:\Documents and Settings\All Users\Application Data delete the Ahead folder & Nero folder if there is one.
7. Start\Search\For Files or Folders\All files and folders Searc for Ahead & then Nero.
Delete any file or folder you find except the various Nero clean tools & other tools you got from Nero techs.Just in case they migh help.
8. Run\regedit Edit pulldown\Find In Find what search for Ahead & delete any key with an Ahead folder. Also any D-word or string value containg Ahead as long as it pertains to Nero. Meanng if some other software is also named Ahead don't delete its keys,etc.
9. Repeat #8 for Nero.
10. Reboot to Normal mode.
Here is something I found in one of the links posted in the link you posted.
Go to Microsoft.com and do a search for "Microsoft.NET 3.0 Redistribution Package." Install it. If you get a message that you already have the most current edition of that file, there is no need to install it.
Go back to Nero.com and download 9.0 from their site. It says "UPDATE" but it is really the full, "Fixed" version o 9.0 Don't RUN it from their site, download it to the desktop. Then install it from there. Do not install from the disk you purchased, use the on-line version. It will look like you are downloading a Trial Version but when the box comes up with a serial number, get rid of their trial number and input the number that came with your purchased version.
On the Microsoft.NET 3.0 if you get a message saying you have a later version you probably want to keep that.
If all that doesn't let it install then I suggest getting a refund & purchase other software & use the freeware when possible.
For .mp4 the software suggested by Kerry56 should work.
I might add DVDFlick .
To rip movies I use AnyDVD for decrypting & CloneDVD2 for ripping,compressing,& burning movies.At least most of the time.I occasionally use ImgBurn for some of this.
ImgBurn will also burn music both as Audio CD & .mp3 data disc.
A software named Burrrn is also a good Audio CD burner.
So if you want to just get rid of Nero you really don't need it.