You can either right click on the Windows button and select Event Viewer or go Start - type eventvwr and press enter when it comes up.
Ensure Event Viewer (Local) is highlighted in the left pane - if it isn't, just click on it.
When it has read the data, click on Critical then on View All Instances of This Event then on the one that reports Hardware error.
Click on View tech details and let me know what it reports.
Use the back arrow top left of page then click on Error and again on View All Instances of This Event.
You are looking for a time stamped error for when you were unable to print the envelope.
Alternatively, try the program again and then check Event Viewer for the latest reported error if different to the previous reported error.
Leave Event Viewer open while you do that.
If a time stamped error exactly matches your attempt to print, click on it which will produce more info in the pane below that.
Click on Copy/Copy details as text in the lower right pane - right click in the forum reply box and select Paste.
I'll then be able to look at it to see if it will tell me anything.
If there is more than one with identical time stamps, copy and paste those as well.