Errors displayed intermittently in the SQL Server Error Log or Verbose LiteSpeed log files when performing backup / restore:

"write failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.)."

"BackupVirtualDeviceFile::RequestDurableMedia: Flush failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.)."

"Operating System Error 995" is a general error message reported when the I/O operation has been aborted because of the thread exit or application request.

During the LiteSpeed backup/restore operation, it would generate one to many processes to accessing the backup file(s). Whenever it encounter a non-recoverable error, it will abort the current threads/proccess.  As a result, "Operating System Error 995" is being log into LiteSpeed Log, SQL Error Log and Application Event Viewer Log

The actual error could be caused by but not limited to the following issues:
1) Resources issues
2) Network issues
3) Configuration issues
4) Memory issues
5) SQL Server issues
6) Third Party issues

Try to reduce memtoleave issues by reducing @maxtransfersize or @threads parameter until backup/restores stabilise. Trial and error is the best, if not direct, method of resolving these types of issues.

The following is an example of LiteSpeed Log indicating there was a network issue:

2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupMedium::ReportIoError: write failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_2'. Operating system error 64(The specified network name is no longer available.).
2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupMedium::ReportIoError: write failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_0'. Operating system error 64(The specified network name is no longer available.).
2009-01-11 04:43:09.14 Backup      Error: 3041, Severity: 16, State: 1.
2009-01-11 04:43:09.14 Backup      BACKUP failed to complete the command BACKUP DATABASE Sample. Check the backup application log for detailed messages.
2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupMedium::ReportIoError: write failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.).
2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupVirtualDeviceFile::RequestDurableMedia: Flush failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_0'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.).
2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupVirtualDeviceFile::RequestDurableMedia: Flush failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.).
2009-01-11 04:43:09.14 spid64      Error: 18210, Severity: 16, State: 1.
2009-01-11 04:43:09.14 spid64      BackupVirtualDeviceFile::RequestDurableMedia: Flush failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_2'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.).

In this case, LiteSpeed was using 3 threads to performing backup.  'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_0', 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1', 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_2' is being generated for accessing the backup file(s).
'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_2' and 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_0' first encounter the network error - "Operating system error 64(The specified network name is no longer available.)."  LiteSpeed then start aborting all the processes. 
The 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1' encountered the abort command before hitting the network error.  So, it received "write failure on backup device 'VDI_25CCCF9E-998A-4DA1-B433-386B20D5E949_1'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request".

Then all the processes also hit the "Operating System Error 995" as a result of the processes abortion.

Note:  This issue has been known to occur on both 4.x and 5 .x versions of LiteSpeed

For trouble-shooting Memory Issue:
To tracking SQL Server MemtoLeave...

FIRST, create the following table:
CREATE TABLE [dbo].[MemToLeave](
[CONTIGUOUSSIZE] [int] NULL,
[RecordId] [int] IDENTITY(1,1) NOT NULL,
[RecordDate] [datetime] NOT NULL CONSTRAINT [DF_MemToLeave_RecordDate] DEFAULT (getdate())
) ON [PRIMARY]

THEN, create a job with the following:
declare @tmp_select char(500)
set @tmp_select = 'execute master.dbo.xp_memory_size'
INSERT INTO MemToLeave (CONTIGUOUSSIZE)
exec(@tmp_select)

This should assist in determining which parameters (-g switch for example) may be best in your setup.

Also, please check the following:  http://support.microsoft.com/kb/934396