Continuous Target Cycling Issues

So I have Target Cycling bound to the Insert/Zero key, and reverse target cycling bound to the Shift + Insert/Zero key.
The issues I'm having is that I get continuous cycling through targets as if I'm holding down Insert/Zero when I'm not touching any keys! This makes playing very difficult because my target keeps changing automatically...
I can get this to happen when I rapidly hit Shift + Insert/Zero at nearly the same time. Is this a feature? It doesn't seem like one to me because it makes playing GLD impossible so I'm guessing it might be a bug...

Time: 6:45PM EST
Frequency: Frequent
World name: Adamantoise
Character name: Mirra Anatol
NPC name: N/A
Monster name: N/A
Class/Level: GLD/27
Party or solo: Party & Solo
In-game time:
Area and coordinates: Anywhere enemy/NPC targets are selectable
Steps:
1. Set up bind keys as indicated above -
2. Go to an area with 3+ selectable Enemy targets
3. Rapidly hit Shift + Insert/Zero many times

Connection Specs
- Type of internet connection/provider: Cable/Comcast
- Modem maker/model number: UBEE

PC Specs
-=-=-=-=- System Information -=-=-=-=-
Core i7 8GB RAM
GeForce GTX650
Keyboard is a Generic USB keyboard

Browser Information
- Name and version of the browser currently in-use: Opera