Excel Custom UI Addin Resets Quick Access Toolbar - excel

Question

I recently created an AddIn to make the lives of my co-workers easier, and to make it as easy as possible for them I made a custom UI to add a tab and buttons for the macros. It works great and everyone is mostly happy. A problem has cropped up on some of their computers where the quick access tool bar gets reset every time they open Excel. Mine also reset the first time, but it's held on to changes I've made since. Other's gets reset every time they open it and I can't figure out why. I built my customUI from scratch and did not use any third party software to do it.
There isn't any code within the AddIn that affects the UI, the only code I put in was a Case statement to run specific macros for specific buttons. Below is my custom UI xml file. Anyone have any ideas why the quick access toolbar keeps resetting?
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
<ribbon>
<tabs>
<tab id = "CRC" label = "CRC Macros" insertAfterMso = "TabHome">
<group id = "MPS" label = "Schedule">
<button id = "KTC_button" label = "KTC MPS" image = "ktc_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "KTS_button" label = "KTS MPS" image = "kts_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "KTV_button" label = "KTV MPS" image = "ktv_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "split_button" label = "Split Schedule" image = "split_icon" size = "large" onAction = "ProcessRibbon"/>
</group>
<group id = "CTB" label = "Shortage Reports">
<button id = "QD_button" label = "Quick CTB" image = "qd_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "PL_button" label = "Product Line or CSV" image = "pl_icon" size = "large" onAction = "ProcessRibbon"/>
</group>
<group id = "OTH" label = "Other">
<button id = "STG_button" label = "Shipments-To-Go" image = "stg_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "peg_button" label = "Format Pegged" image = "peg_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "MRP_button" label = "MRP Summary" image = "MRP_icon" size = "large" onAction = "ProcessRibbon"/>
<button id = "MPS_Sum_button" label = "MPS Summary" image = "MPS_Sum_icon" size = "large" onAction = "ProcessRibbon"/>
</group>
</tab>
</tabs>
</ribbon>
</customUI>

Answer 1

Your ribbon XML markup looks good. It cannot be related to resetting the QAT in Office applications (Excel in your case) from the first sight.
First of all, you need to check out the list of Office add-ins. There can be any conflicts between extensions and your customizations.
Second, make sure there are no UI errors in Excel. By default, if an add-in (or any other kind of ribbon customizations) attempts to manipulate the Microsoft Office user interface (UI) and fails, no error message is displayed. However, you can configure Microsoft Office applications to display messages for errors that relate to the UI. You can use these messages to help determine why a custom ribbon does not appear, or why a ribbon appears but no controls appear. See How to: Show Add-in user interface errors for more information.
Third, it is not clear what your callbacks do. But ribbon is a static thing from its birth, so QAT can't be customized at runtime without loading a custom ribbon XML. So, only users or add-ins could do resets.