Trying to open a serial port with pyserial on WinXP -> "Access denied"

I'm trying to send data to an hplc pump via the serial port using python and pyserial. I tested the cable and the pump under linux (a gentoo derivative), where it worked perfectly, albeit as root. Now i have to use the code on a WinXP machine, where i always get an "Access denied" error when trying to open the port (i adjusted the parameters to COMxx instead of ttySxx, the port is found). I tried the serial port of the computer, as well as a USB2Serial adapter. I heard that WinXP was quite restrictive when it comes to trying to address some port with self written code. Is there a simpler workaround for this problem than installing linux? ``` # -*- coding: utf-8 -*- import sys import time import serial from threading import Thread """ usage: cmdCapture workDirectory pictureTime pressureTime """ print 'successful import is successful' workDir=sys.argv[1] pressureThresh=float(sys.argv[3]) class doCapture(Thread): def __init__ (self, workDir, pressureThresh): Thread.__init__(self) self.workDir=workDir self.pressureThresh=pressureThresh self.pressureTimer=0 ``` -> here i set the serial port ``` self.ser=serial.Serial(port='\\.\COM1', baudrate=9600, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=1) ``` -> here the error happens ``` self.ser.open() def getPressure(self): self.ser.write('PR') return self.ser.read(size=8), timer.timer() def run(self): self.pressureTimer=time.timer() while 1: if self.pressureTimer<=(time.timer()-self.pressureTime): self.p=getPressure() print self.p myCapture=doCapture(workDir, pressureThresh) myCapture.start() ```