I only know about Facebook that it is part of a FAQ.
The reason - Facebook will only give You yeoman service if You set K-Meleon's
UserAgentString to camouflage as Firefox. That is done via the Tools menu UserAgent item, the Privacy Bar -> right click on User Agent & select Firefox or else via a dedicated extension called AutoSwicher that changes Agent to Firefox whenever You come to a page that You have added to its shoddy pages list.
No - it is no stupid question of You - it is outright insane of Facebook, Hotmail, Yahoo mail and other pages that use a pathetic browser switch that is based on a white list,
which does not know K-Meleon and several other browsers.
Detailed info about the whole issue.
Rule of thumb: if a page dis-behaves fake Firefox User Agent String.
It solves the problem in 9/10 cases.