Sometimes the curser goes missing on some search engines and forums.I had to restart kmeleon to get it back.

I am using kmeleon 1.5

What Windows version are you using?
Do you like said mouse cursor?

K-Meleon in Spanish

No, mouse curser is there,the missing curser is typing in for sites like wikipedia.

the text pointer can act-up for several reasons.. for example if you're using a custom cursor that has many colours(64bit) more than supported than the os. a friend once had a similar problem when he used vista aero whatsit cursors on an xp pc. so if that's the case, make sure to use the default windows text pointer:
control panel>mouse>pointers>text select>'use default' button.

another reason could be if you're using a laptop, the touchpad sometimes causes this problem if for any reason something moves on it(tiny spider?).. then try this tool called touchfreeze: http://code.google.com/p/touchfreeze/

no custom curser and not a laptop.

it could be a bug, please state your windows version and the site where it happens often.. someone will try to reproduce it if possible