The Submit for approval window which appears after the "Submit for Approval" button is clicked in the PO is randomly disappearing. The workaround in order to reappear is to close and reopen the client or change the company, open the PO window and change to the original company again. It seems that the window appears for a while and then is hidden.
Just check if the user did changed his GP password. I have encountered that situation in an environment where the user has the AD and GP account as the same. After changing his windows password, he didn't change his GP password and never logged off GP since changing his password. So, after changing his GP password and logged off GP and back in, the issue was resolved. The workaround that issue has always been to log off GP and log back in. And it always had worked for me.
thanks for your response. Unfortunately this is not the issue. I can reproduce the error with any user. Basically the "Submit for Approval" window in the PO works fine only in the first logged company. If I change to another company and I click the "Submit for Approval" button in the "PO Entry" Window, the "Submit for Approval" window appears and then suddenly disappears. The only way to fix it is to change to another company, open the "PO Entry Window" and change again to the company with the problem. It seems that something in the change company process is affecting the "Submit for Approval" window to maintain it visible.