Strange, looks like your Tahoma font might be corrupt.
If you open Notepad, go to the Format menu, "Font", and then choose Tahoma, do you see a "Regular" option?
If not you could try downloading the Tahoma font from the internet and installing it, see if that fixes the problem.
If you open Notepad, go to the Format menu, "Font", and then choose Tahoma, do you see a "Regular" option?
If not you could try downloading the Tahoma font from the internet and installing it, see if that fixes the problem.