CDrom on the on the optiplex 760 ultra slim keeps disconnecting

Our company got in some OptiPlex 760s (the smallest one's you can buy with the laptop CDrom).  For some reason all of them drop the D:\ drive every once in a while.  If you restart, it's fine but they seem to keep dropping.   A workaround is that you can pull out the CDrom unit and push it back in.  Windows will redetect it and assign it a drive letter.  Any ideas as to what is causing this?  I know it's not a hardware issue because all of them are doing it.  I've updated the Bios and flashed the CDroms but they still keep dropping out of Windows.  For reference we are using Windows XP Pro (SP3).  Any help would be appreciated. 

This is what I see in the event viewer:

Event Type: Error
Event Source: Cdrom
Event Category: None
Event ID: 11
Date:  3/17/2010
Time:  10:34:44 AM
User:  N/A
Computer: Z08813
Description:
The driver detected a controller error on \Device\CdRom3.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 03 03 68 00 01 00 b8 00   ..h...¸.
0008: 00 00 00 00 0b 00 04 c0   .......À
0010: 01 01 00 00 00 00 00 00   ........
0018: 00 00 00 00 00 00 00 00   ........
0020: 00 80 00 00 00 00 00 00   .€......
0028: ea 87 0a 00 00 00 00 00   ê‡......
0030: ff ff ff ff 02 00 00 00   ÿÿÿÿ....
0038: 40 00 00 c4 02 01 00 00   @..Ä....
0040: 00 20 0a 12 4c 02 00 00   . ..L...
0048: 00 08 00 00 0a 00 00 00   ........
0050: 00 a0 0e 89 38 88 74 88   . .‰8ˆtˆ
0058: 00 00 00 00 70 37 64 88   ....p7dˆ
0060: 00 00 00 00 10 00 00 00   ........
0068: 28 00 00 00 00 10 00 00   (.......
0070: 01 00 00 00 00 00 00 00   ........
0078: 70 00 04 00 00 00 00 0a   p.......
0080: 00 00 00 00 3e 02 00 00   ....>...
0088: 00 00 00 00 00 00 00 00   ........

Event Type: Error
Event Source: PlugPlayManager
Event Category: None
Event ID: 12
Date:  3/17/2010
Time:  10:29:33 AM
User:  N/A
Computer: Z08813
Description:
The device 'TSSTcorp DVD+-RW TS-L632H' (IDE\CdRomTSSTcorp_DVD+-RW_TS-L632H_______________DW30____\4&2f700bdf&0&0.1.0) disappeared from the system without first being prepared for removal.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 00 00 00 00               ....   

I searched something similar on Microsoft's website and found this, but it does not help:

Windows XP

1. Click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. In the navigation pane, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
4. In the right pane, click UpperFilters.
   
   Note You may also see an UpperFilters.bak registry entry. You do not have to remove that entry. Click UpperFilters only. If you do not see the UpperFilters registry entry, you still might have to remove the LowerFilters registry entry. To do this, go to step 7.
5. On the Edit menu, click Delete.
6. When you are prompted to confirm the deletion, click Yes.
7. In the right pane, click LowerFilters.
   
   Note If you do not see the LowerFilters registry entry, unfortunately this content cannot help you any further. Go to the "Next Steps" section for information about how you can find more solutions or more help on the Microsoft Web site.
8. On the Edit menu, click Delete.
9. When you are prompted to confirm the deletion, click Yes.
10. Exit Registry Editor.
11. Restart the computer.

Thanks!