detailed issue is there : http://www.zabbix.com/forum/showthread.php?t=8510

And re-written there:

Hi,

I've got something special when a file is higher than 2Go it's recognize as size of 8388608 To.
Information :
Zabbix server 1.4.2
Zabbix agent 1.4.2
Filesystem Type NTFS
Windows 2000 server

Result log :

2007.Dec.10 18:04:09 9223372036854775807
2007.Dec.10 18:03:39 9223372036854775807
2007.Dec.10 18:03:10 9223372036854775807
2007.Dec.10 18:02:39 9223372036854775807
2007.Dec.10 18:02:09 2139103232
2007.Dec.10 18:01:40 2115510272
2007.Dec.10 18:01:32 2108956672

Item used:

vfs.file.size[I:\oracledb\MIGJV\oradata\TEMP01.DBF]

Zabbix_get result :

1. zabbix_get -s ****** -k "vfs.file.size[I:\oracledb\MIGJV\oradata\TEMP01.DBF]"
   18446744071709007872

Real size:

2,13 Go (2 294 423 552 octets)

in attachement :

-trigger window
-Item conf

Regards.

Ben