problem when update counters after change my server

[brave24]

<font color="Magenta">hello

i have problem after i change my server . i donot make any changes in security and back all to default and no any disable funtcion and safe mode even is off

but the one thing is new in this server it is setup Mod Security with no rules and alsoo installed xchach to speed my sites and nothing new other these two so i,m asking what the reason of this error coz first time happen with me

this is error when update counters / rebuild attachment thumbilans

Maintenance

Building Attachment ThumbnailsIf you receive a fatal error or if the process seems to hang, you will need to delete the last attachment listed on the screen then refresh this window.

Warning: tempnam() has been disabled for security reasons in [path]/rootcp1/misc.php on line 689

Warning: fopen() [function.fopen]: Filename cannot be empty in [path]/rootcp1/misc.php on line 691

Warning: fwrite(): supplied argument is not a valid stream resource in [path]/rootcp1/misc.php on line 692

Warning: fclose(): supplied argument is not a valid stream resource in [path]/rootcp1/misc.php on line 693
Processing: Attachment : (JPG) [20] (Post : [11256] ) Error: Attachment Missing

Warning: tempnam() has been disabled for security reasons in [path]/rootcp1/misc.php on line 689

so plz any help to know what is the reason the two thing new in my server ( Mod Security and xcache ) nothing else and not happen with me this error before

plz any advise?</font>