Another symptom:
When the corruption happens I do the following steps:
1) I press ALT-F1 to switch to the dumb terminal screen but it has no display at all.
2) I press ALT-F7 to switch back to X terminal screen and the corruptions have been removed.
3) I press ALT-F1 to switch to the dumb terminal screen and it displays as normal.
My conclusion to this is that when suspending, the full state of the graphics card is not being saved.
Another symptom:
When the corruption happens I do the following steps:
1) I press ALT-F1 to switch to the dumb terminal screen but it has no display at all.
2) I press ALT-F7 to switch back to X terminal screen and the corruptions have been removed.
3) I press ALT-F1 to switch to the dumb terminal screen and it displays as normal.
My conclusion to this is that when suspending, the full state of the graphics card is not being saved.