Originally Posted by Sersanah 
Are you becoming encumbered and then dropping/eating/using an item to lower the weight but remaining encumbered even when the new weight total is below the encumberance threshold? If so, you will have to shift an item in inventory and it will fix it - this is a bug that I don't believe was ever addressed with patches.
No, I mean I don't understand what the encumberance threshold is. For instance, it shows a number like 1570/2200, and I assume the first number is my current weight, while the second number is my maximum weight. I get encumbered when I go over a certain amount, even though it's well below my maximum.