Inequality strings not processed properly

Have enabled both the LaTeX renderer and the Blahtex renderer in the same input format?

I also have this problem with > and < not generating correctly. If could be because these relations do not have values within latex but use the normal > and < keyboard symbols

I use DruTeX extensively for my web site. I did encounter the problem before but has solved it.

Cause:
The problem is NOT due to DruTeX, but by other filters. I think no MathML is involved too.
Some input filter will 'escape' dangerous characters (such as <, >) to its HTML equivalents BEFORE DruTeX had a chance to process it. So when you write $x<y$, the filter converts it to $x&lt;y$, and only then DruTeX does the processing by converting it to an image. So you get the wrong result.

Solution:
Force the DruTeX filter to process prior to other filters. It's generally quite safe to do so.
Go to administer -> Site configuration -> Input formats -> configure (for each input format with DruTeX) -> 'rearrange them' (found in the 2nd paragraph of the top comment). Assign '-10' to DruTeX.

Hope it helps.