Windows 7 - external USB HDD no longer performance optimized

hello forum,

all of a sudden my external HDD (USB) is no longer performance optimized.
usually the properties window of the device has a tab "policies" where you can choose between "quick removal" and "better performance".

after recent system changes (BIOS update, windows updates, formatting the external HDD) i observed very poor performance.
i then noticed the following:
1) the device no longer shows up in systray / notification area for safe removal
2) the properties dialog no longer has the policies tab!

so it looks like the operating system has permanently activated the "quick removal" (write caching disabled) now and won't allow me to change it to "better performance" (write caching enabled, systray icon for safe removal).
but why?
and how to change it back?


some additional notes notes:

a) windows 7 is still showing proper behaviour for other removalbe devices (e.g. USB thumbs driver). it seems to be specific to my external HDD.

b) the external HDD is formatted with NTFS.

c) this is a dual boot system (Windows 7 x64, win xp x86). my external HDD doesn't show those symptoms when booting into windows xp. so i can rule out the bios update as root cause. it seems to be specific to Windows 7.

d) my system has 12 GB of RAM. so the full memory is visible to Windows 7 x64, but only 2.5 GB is visible to winxp x86.

any ideas?