Fragmented and amassing file problems

My PC runs slower and slower as the hard disk fills up. I find the problem is thousands of files associated with my Norton Internet Security.

 

Hundreds of folders are type  \WINDOWS\Temp\slu****.tmp .

Hundreds of folders are type  \Program Files\Common Files\Symantec Shared\VirusDefs\tmp****.tmp
  where **** is four digit hex.

The files are NAVEX12.DAT,  NAVEX32a.DAT, TCDEFS.DAT, TCSCAN7.DAT, cceraser.dll, esrdef.bin,
  VIRSCAN*.DAT (where * is 1 to 9).    [not always CAPS]

 

In addition, all but four of my badly fragmented files are associated.

Here is the list.

 

Fragments       File Size       Files that cannot be defragmented
2,436           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp13a8.tmp\VIRSCAN7.DAT
1,964           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp3d38.tmp\VIRSCAN7.DAT
2,334           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp4841.tmp\VIRSCAN7.DAT
2,201           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp670e.tmp\VIRSCAN7.DAT
2,213           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp542e.tmp\VIRSCAN7.DAT
2,121           112 MB          \WINDOWS\Temp\slu5aac.tmp\VIRSCAN7.DAT
2,375           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp5dec.tmp\VIRSCAN7.DAT
2,380           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp75f8.tmp\VIRSCAN7.DAT
2,310           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmpb98.tmp\VIRSCAN7.DAT
2,495           112 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp159f.tmp\VIRSCAN7.DAT
2,152           114 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp5bea.tmp\VIRSCAN7.DAT
1,888           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\BinHub\VIRSCAN7.DAT
2,350           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp5e1c.tmp\VIRSCAN7.DAT
2,615           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp1782.tmp\VIRSCAN7.DAT
2,159           119 MB          \WINDOWS\Temp\slu1d18.tmp\VIRSCAN7.DAT
2,091           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp2456.tmp\VIRSCAN7.DAT
2,476           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp50dd.tmp\VIRSCAN7.DAT
2,062           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp6d8e.tmp\VIRSCAN7.DAT
1,841           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp7a87.tmp\VIRSCAN7.DAT
2,523           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp7dce.tmp\VIRSCAN7.DAT
1,957           119 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp4d63.tmp\VIRSCAN7.DAT
1,927           119 MB          \WINDOWS\Temp\slu2456.tmp
1,843           119 MB          \WINDOWS\Temp\slu7b10.tmp\VIRSCAN7.DAT
1,929           121 MB          \WINDOWS\Temp\slu1d1b.tmp\VIRSCAN7.DAT
2,913           121 MB          \Program Files\Common Files\Symantec Shared\VirusDefs\tmp71be.tmp\VIRSCAN7.DAT
1,955           122 MB          \Documents and Settings\All Users\Application Data\Symantec\Norton Internet Security\URLLists

 

QUESTIONS:

Should all these files be accumulating?
How can I reduce the load they create?

(I am loathe to delete without advice, and find that Norton web pages do not permit me to post a query directly for reasons I cannot fathom.)