my stat increases don't seem to stick.
After you distribute your stat points, you need to confirm them by clicking on the checkmark button on the bottom of the stat window. If you are playing at a low resolution (like on a netbook) the bottom of the stat window could be hidden behind the UI at the bottom of the screen. Click on the window and move it up. screenshot of the stat window
(showing initial, levelled, distributed and confirmed stats).
Unfortunately, there is a bug where if you save the game and reload it, any distributed bu unconfirmed stat points will be lost. In that case, you can use iZakaroN's SaveEditor
(listed below the disk version patch and item editor) to give yourself back those stat points (5 points for each level that you went up, assuming you distributed and lost them all).
If you wait long enough for any food/potion/spell effects to wear off and remove all equipment with stat bonuses (or make sure to take them into account), then the sum of
strength + agility + intelligence + constitution + any unassigned stat points
should be equal to
40 + 5*(Character Level) + possible other bonuses you would only encounter if you explored a fair bit away from Aleroth