First make a backup in case anything goes wrong:
So I opened up my test world and tested it. Thaumometer looking at reinforced obsidian is basically a instant crash. As for fixing it you have two choices that I can think of. The simplest and most destructive is deleting your player.dat. This will destroy your entire inventory but you'll be back at spawn and no thaumometer to look at the obsidian.
The second assumes that you can use a very basic program and find your world's save folder, doing it this way should result in absolutely no loss of data. Go here
http://www.minecraftforum.net/forum...65-nbtexplorer-nbt-editor-for-windows-and-mac and find the download for windows or mac and download the zip for NBTExplorer. run the program and open up the level.dat file in your world's save inside the program. In NBTExplorer under the Level.Dat section will be a data section and then a player section. Inside the player section is a section labled Pos. This is your player's position in the world. Change it. To do something simple add say 50 to the first number and set the second number to 200. This will move your +50 in the X direction in the world high up in the air so you aren't stuck and suffocate when logging in. If you don't have a jetpack or want you might also want to go further down and set playerGameType to 1, this will put you in creative mode so hopefully when you log in and hit the ground you won't die or if this moves you above the void you can fly away back to your base.
After making all those changes save them and then reload your world. Hopefully you should now be at the new location safe and sound and now you just have to avoid using the thaumometer to look at the reinforced obsidian until the bug gets fixed.
