It's not my problem. User Reported this in our community facebook group and am reposting this for him. as per his comment This Problem is in Firefox using Malayalam Wiki (Chrome have no problem). Tamil Wiki Working Fine and also ml.wikisource.
Cannot reproduce with Firefox 18 on Fedora Linux on http://ml.wikipedia.org/wiki/പ്രധാന_താൾ . Does that still happen after clearing the browser cache, see http://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache ? Is there any error output under "Tools > Web Developer > Error Console" in Firefox when this happens?