Keep getting Medium error

I have been getting this error whenever I try to burn a disc through Toast:


I don't understand why, could it be due to how old the discs are possibly? After I receive that error, it shows up 4 more times, and then it says writing lead out, and now i can't use the discs anymore. I then try popping it back into the drive, and try to open it up in Finder, and it says i don't have permission for this task which makes absolutely no sense. I have tried making a DMG of the files I want to burn through Toast and that works, but I go into Disk Utility to burn it, and it says the disc isn't supported by my drive. Now I have been having issues with CDs as well, where when i burn a music disc through Toast and iTunes, random songs throughout the disc have static at higher frequencies in the song.

So what could be the problem?

Sadly I have found that this is normally a sign of the disc burner on it's way to burner heaven.
You could certainly try the usual cleaning methods first, and also try a different disc brand, as it can be the discs too (memorex have never worked for me for example).
If you are getting problems in Disk Utility as well as Toast, it's not Toast that has the issue.

Oh woohoo, this isn't the first to die on me either. I guess it's time to push up my goal to put an SSD in its place. But until then, I am using memorex discs, and I have unfortunately had a rough time with them as well. Think they might be it?

For certain it could well be.
It's been realtively well documented that certain Mac burners do not like them at all, and never burn to them.
I stick with Imation, Sony or Verbatim.
I'm confused now though, why do you say put an SSD in it's place? You'd have no burner!
On that note, far cheaper to buy an external burner than replace the one in the Mac.

My plan was when he Lacie blu-ray burners dip further down in price, I was going to get an SSD to replace my Superdrive, and had the Lacie as an external. Now i do have another external at home, I just don't have it here at school.

Ah ok.