How to detect the presence of a html file

[Phoe6]

Operating System: Windows
Python version: 2.4

I have bookmarks.html and wumpus.c under my c:

When I tried to check the presence of the bookmarks.html, I fail.

>>> os.path.isfile('c:\bookmarks.html')
False
>>> os.path.isfile('c:\wumpus.c')
True

>>> os.path.exists('c:\wumpus.c')
True
>>> os.path.exists('c:\bookmarks.html')
False

>>> os.access('c:\bookmarks.html',os.F_OK)
False

I can assure you that c:\bookmarks.html exists! and I opened this and
checked it in the browser as well.

Why is this behavior? And How Should I check for the presence of this
file?

Any help appreciated.

Thanks!
Senthil