So I bought the particular recorder, Tascam DR 05. I've had it for about 2 months now. And of late the screen has started "freezing" randomly. During this I am unable to shut it down unless I take one of the batteries out. During this freezing the screen starts to "erase" slowly and then "de-erase" meaning the screen slowly comes back as it was.

A simplified example: On a screen, you have A B C D E. It freezes and the previously mentioned erasing starts. Now it shows B C D E, then C D E etc. Then after there's is nothing but empty screen the content starts to come back: A then A B then A B C etc.

It's extremely annoying and the recorder itself cost about 100€ and it can't be returned anymore. Any ideas what's going on and what could be done?
Did you buy it new? If so, whether the store likes it or not you're still under warranty & can take it back.
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Look up firmware updates and see if you can apply them.
It could be overheating issue, so see if you can possibly keep it so it doesn't get warm (if it does), or at least see if that might be the issue.
Contact Tascam and see what they'll recommend.