Can't see some NPC's

[camoss16]

Hey guys I joined P99 about a month ago wanting to relive the old days when EQ was awesome. Anyways when I first started up my human necro I thought it strange I never saw any rats in East or West Freeport newbie zones. About a week or two later I went to befallen to try out my new ward undead spell to find myself being attacked by plague rats I couldn't see. I can't target them by clicking on them but if I /assist my pet I could then target and attack the rats, though they still weren't visible to me. They don't show up when I have deadeye on either.

Oh well, I thought, if I never see another rat again no big deal. Well about two days ago I went to Oasis to try my hand at crocs with my now 13 necro but I can't seem to see or target them either. I can't see Dorn in North Ro or the Sisters of Erollisi in OOT. I also can't see elementals/mage pets. It seems to be random though because I can see Dark Elf players and other Dark Elf NPCs (at least I can see the guards in Nektulos Forest) and Wood Elf NPCs (Vendors in OOT).

I'm running the Titanium client on an older Windows XP PC. I used Duxa's all in one installer to get the game going and other than these nonvisible NPCs I haven't had any problems. Has anyone else had this problem? Any ideas on how to fix it?