As Gustavo suggested, I think seeing the Tracklog Layer Properties dialog window will help in determining if there is a pathing issue which might be causing the error you are encountering. Please view the attached screenshot and confirm that there is not a double slash "\\" in the path name of the tracklog.shp filename. [ATTACH=CONFIG]18717[/ATTACH] With older versions of ArcPad, I have seen users encounter the "Error opening or creating the track file '\\My Documents\Mydirectory\Tracklog.shp.' Check preferences." Let's check to see if its related to your ArcPadPrefs.apx file. First close ArcPad on the desktop PC then Open Windows Explorer and navigate to the ArcPadPrefs.apx file. It's stored in the \My Documents\My ArcPad folder on WinXP PCs and Windows Mobile devices; its stored in \Users\profile\Documents\My ArcPad folder on Win7 PCs. Rename ArcPadPrefs.apx to oldArcPadPrefs.apx and launch ArcPad on desktop PC, ArcPad will open with default parameters restored. We renamed the file so as not to lose any customizations you may have.
Check the Tracklog functionality, do you still see the error message? If not, then likely there is something in the ArcPadPrefs.apx file that was altered somehow and if you have no customizations you can continue using ArcPad with the new ArcPadPrefs.apx file from this point forward. Yet if you do have other customizations in your ArcPadPrefs.apx file you can resolve the error by editing the ArcPadPrefs.apx file in XML editor utility such as Notepad. Again, Close ArcPad on the desktop PC before editing the ArcPadPrefs.apx file. Using Edit menu > Find "tracklog" to quickly navigate to TRACKLOG option, remove the double slash "\\" in the path name of tracklog.shp filename or if the .shp extension is missing as your error would seem to indicate, add it to the tracklog.shp filename. Save and close the modified ArcPadPrefs.apx file then launch ArcPad, ArcPad will open with newly modified ArcPadPrefs.apx file. Check the Tracklog functionality, do you see the error message at this point? [ATTACH=CONFIG]18719[/ATTACH]
If neither of those suggestions helps resolve the error, I did find another user who reported they performed complete uninstall and re-install of ArcPad to resolve the "Error opening or creating the track file '\\My Documents\Mydirectory\Tracklog.shp.' Check preferences." error. If you are still experiencing problems with this error I encourage you to contact Esri Support and submit a support interaction so you can work with ArcPad specialist to resolve this error message and utilize GPS Tracklog functionality in ArcPad.
