Don't know what system you are using, but the Tex and Algebra use programs outside of moodle to do their stuff. I too had the "Undetermined Error" for the ALgebra filter and a search through the forums didn't give me a clear answer but some clues!
I'm running an Ubuntu Linux server with all the latest versions of software. Seems the default install of Perl (the program the Algebra filter uses) under Ubuntu does not have all the required Perl modules installed. I needed to install these two:
How you install and enable these are dependent on what type of server you are running. And in my case, a firewall prevented me from using the inbuilt Perl CPAN install utility, so I had to it manually.
How did I work out what I needed? I simply ran the Algebra filter perl script on the command line and looked at the errors! On my system it was:
I suspect the problems with the Tex Filter are also due to not having the correct "helper" programs installed or configured!