Hello DSAIJA.
If you have not already resolved this issue, we suggest you search our online knowledgebase for this product: WorkCentre 78xx.
Alternatively, you can visit our Contact Us page for other support options.
We are having the following issue on the 78xx;
Once a while the alternative log on function does not work properly. If the issue accurs, we can restart the MFP and it works again for a short period of time.
We double checked all our configurations and can not find any obstacels which may cause this issue.