Drive a vehicle.
Access the inventory, and swap items to and from the vehicle inventory.
Exit the vehicle and test the reload command.
If the gun fails to reload, or you cannot swap weapons or pick up/drop items then this seems to indicate the bug is present.
Binoculars and medical items can still be used.
It happens at random, certainly not every time.
[*edited steps for reproducability]
This has been tested in Conflict Everon and Arland, including the single player game as well as server based.