No problem here!
Maybe you've (perhaps unintentionally?) been playing around with "Key definitions & WinLIRC" under Options > Preferences?
Anyhow:
check (for both "Windowed mode" and "Full screen mode")
the defined value of "Full screen switch"
(should be [F] resp. [Mouse Left+DblClick])
and check (for "Windowed mode")
the defined values of Resize movie window - and Resize movie window +
(should be [Wheel down] and [Num -] resp. [Wheel up and [Num +]).
(The values mentioned as "should be" are the
default values).
To restore all default values in one go (
losing all your changed settings!), you can also (while BSPlayer is
not active!) rename or delete the file "
BSplayer.xml" in (WinXP) C:\Documents and Settings\
Yourname\Application Data\BSplayer\ (or \BSPlayer Pro\) and after that start BSPlayer again.
(P.S.: Which version of BSPlayer are you presently using?)