Error at line 9655 (2) !Link Error Code: 00800(HEX),

Let's get you back up and running, Desktop_Rookie.

There are several possible reasons for this issue and several solutions to resolve this. It could be that:

• The system in the multi-user mode does not have the latest release of QuickBooks.
• Corrupted QuickBooks company files
• Client and server domains are not matching to each other.
• QuickBooks installation was damaged
• Damaged QuickBooks installation files

To better isolate the issue, you'll need to log into Windows as an Administrator. After that, open Windows in safe mode and disable the antivirus software installed on your system. Once done, let's rename your QuickBooks Desktop company file. 

Here's how:

1. Back up your QuickBooks company file (ensure you have an extra back up of your company file).
2. In QuickBooks, check the location of the company file.
   • While on the Home page, press F2 or Ctrl+1 to open the Product Information window.
   • Note the location listed in the File Information field.
3. Go to the location specified.
   • Right-click the Windows Start button and select File Explorer (Windows 10, 8.1 and 8)  or Open Windows Explorer (Windows 7 and Vista).
4. Right-click the file and select Rename. The file name may appear as [CompanyName].qbw or just [CompanyName].
5. Change the file name and press Enter.
6. Select Yes to confirm the action.

Set up QuickBooks Desktop to use the new company file name

1. From the QuickBooks File menu, select Open or restore an existing company.
2. Select Open a company file and click Next.
3. Select the newly renamed company file and click Open. If you are in a multi-user environment, you need to open the renamed company file on all workstations.

See these articles for detailed steps and instructions:

• Rename your QuickBooks Desktop company file
• .ND files in QuickBooks Desktop

Please get back to me if you still need help with the steps. I'll be around to lend a hand. Keep safe and have a good one!