LaTeX reads in files to process one line at a time. Normally, this works out okay, because a line with carriage returns is about 70 characters, and that's not too much for LaTeX to think about at one time. However, if you are creating your .tex file in an editor that doesn't have word wrapping on, then one line can last for the entire paragraph. If the paragraph is very long, then this can be more than LaTeX can handle at once, and you'll get an error message of something like
(under LaTeX 2.09, it would say
but the meaning was the same).
Regardless of the error message, you shouldn't try to change the LaTeX configuration to fix the buffer size - what you need to do is edit your file to insert line breaks. In emacs, you can "fill" a paragraph by hitting M-q with the cursor in that paragraph, or type
to fill the entire document.
Sometimes this error will be generated by the inclusion of a postscript file, instead of by the .tex file itself. This is most frequently the case when the postscript was generated on a Mac; Macs use ctrl-M for a line break where UNIX uses ctrl-J (and Windows/DOS uses ctrl-M plus ctrl-J). The simplest way to fix this is to load the postscript file into emacs, and run
to replace all the ctrl-M's with ctrl-J's.