BUG #4761: service not starts

The following bug has been logged online:

Bug reference: 4761
Logged by: Roberto Colmegna
Email address: rcolmegna@tiscali.it
PostgreSQL version: 8.4.0-1b1
Operating system: win XP SP1
Description: service not starts
Details:

Hi,

I have installed the 8.4 beta on a previous installed
8.3 WinXP PC. The PC isn't registered in an active-dir
environment.

Starting 8.4 service I obtain this error:

%t FATAL: could not create lock file "postmaster.pid": Permission denied

The error is accessibile via eventvwr.

No way found to start PG 8.4 ... :(