Vista - Gadget Always On Top Problem

when i deattach a gadget from the sidebar and set it to always on top, it
used to alwas saty on top, normally !! but lately this has changed!! by time
and strangely it satrted to go behind other windows. well it happens
sometimes when i pen my computer, sometimes when i open the internet
explorer. then i have to deativate the always on top option and then
reactivate it, and this doesn't stay forever too, after a while it sinks back
again!!! i tried multiple gadgets and yet the same problem!!!
what could this be???? help me coz it's really annoying!! thxxxxx