If you have a pre-1.0034A CD version of the game, then the
patch should automatically fix the resistance bug. A small number of people reported that the patch did not help, or that they already had the latest version of the game when it occurred. In those cases, either hex editing or using the save editor repeatedly to re-learn Magic barrier is necessary.
The main resistance bug occurred in unpatched games, and was caused by unequipping something with a Magic Barrier skill without otherwise knowing it. Learning one or more levels should help with this, rather than make things worse. There have been other bugs or glitches that have caused negative resistances. To be safe you may want to avoid equipment with that bonus so this doesn't happen again, but I don't know if you would need to avoid learning the skill as well.
In any case, you should eventually get plenty of resistance bonuses from your equipment, and can always purchase Spell Shield spellbooks.
Some people have also run into problems with their sight range calculations, especially when mixing the passive skills and skill equipment bonuses. A couple people found that they could safely mix sight skills if the combined level wasn't above 4 or 5, but that wasn't the case in general.
I don't recall if your sight range is shown in the stats somewhere, but the 'hex offsets' link above describes where the value is in the data.000 file.
I learned a level or two of Elven Sight near the start of the game, but half way through (or so) I started avoiding equipment with sight range bonuses, to keep my sight range not too much larger than the screen size (so I could use the fog of war to help keep track of where I had explored). Your sight range doesn't seem to be bug related, unless you are clearing half the map, or something.
DAD's item editor could remove sight bonuses from your equipment (don't know if it has been tested with the download version of the game).