pythoncom, CoUninitialize & references

[gloom]

Hey,

I'm programming something with NeroSDK COM module, and I bumped into a
problem:
why doesn't python releases and uninitializes COM objects that are no
longer referenced?

Here is a sample code:
# start of sample code
from win32com.client import *

nero = None

def find_backpack_cd():
drives = nero.GetDrives(constants.NERO_MEDIA_CD)
rc = None
for d in drives:
if d.DeviceName.find("BACKPACK") != -1:
rc = d
break
del(drives)
print rc
return rc

def main():
global nero
nero = Dispatch("Nero.Nero")
cd = find_backpack_cd()
del(cd)
del(nero)

if __name__ == "__main__":
main()
print pythoncom._GetInterfaceCount()
pythoncom.CoFreeUnusedLibraries()
pythoncom.CoUninitialize()

# end of sample code

the problem is as follows, if for example, I remove the line
'del(nero)' in function main(), the _GetInterfaceCount() is 1 and
CoUninitialize() fails.
And if I remove the explicit call to CoUninitialize() (and the
interface count is greater than 0) the next time I run the program it
fails with exception that the neroAPI is already initialized (deducing
that it is somehow still in memory).

Doesn't python should get rid of all instances of the COM objects
through its garbage collector?
Thanks,
Omer.