Can someone help me with this error? Missing PDO extension & MySQL Driver!

[s240chan]

I'm trying to install TinyBoard. Which is an imageboard software, similar to 4chan (but this is completely Safe For Work). It was working before, but I decided to start from scratch again. Installations before this went OK, no errors. But this time, it's not working! Usually it would have 0 errors. But this time it has 2! The 7 warnings is normal.
Here is what the error looks like.

 

[Dead-i]

Hi,

This is affecting the server "xo2", and is currently being worked on. Sorry for any inconvenience caused.

Thank you,

 

[s240chan]

Ah! Thank you for the heads up!

 

[twoforty]

Huh. It was working now. Now it's not!