Before starting to troubleshoot turning addons on & off, try this macro:
Code:
/script
DurabilityFrame:SetPoint("CENTER", UIParent, "CENTER", 0, 0)
if not DurabilityFrame:IsShown() then DurabilityFrame:Show() end
This should relocate the DurabilityFrame to the center of your screen and show it if it is hidden. If this macro does not make that happen, then an addon is definately getting in the way of it. First attempt disabling simpleMiniMap and DurabilityFu and check it...since those are known to primarily and directly affect the DurabilityFrame.
The frames primary anchor is typically the MiniMapCluster, so anything affecting that frame is going to probably affect the DurabilityFrame paper doll. Good luck