Web Part properties, error message: "The file is not checked out. You must first check out this document before making changes"

I was updating web part properties in code and I wanted to save them. I called
SetPersonalizationDirty(); after my code had updated the web part properties.


I got the following error message "The file is not checked out. You must first check out this document before making changes"

The reason for this error occuring is because I was calling the SetPersonalizationDirty(); on the OnLoad method. After I removed it and put it straight after my code which updated the web part properties, the web part worked fine and the page did not through the error message "The file is not checked out. You must first check out this document before making changes"