[OpenAFS] Max number of files in volume?

[Hamie]

is there an artificial limit on the number of files in a volume? or the 
root of a volume? I'm running openafs and have a volume such as

br01ai01:/# vos examine mail.qu.viri
mail.qu.viri                      536871081 RW      10329 K  On-line
    mgw01 /vicepa
    RWrite  536871081 ROnly  536871082 Backup          0
    MaxQuota     200000 K
    Creation    Fri Nov 28 16:51:57 2003
    Last Update Thu May 13 10:18:02 2004
    1229430 accesses in the past day (i.e., vnode references)

    RWrite: 536871081
    number of sites -> 1
       server mgw01 partition /vicepa RW Site
br01ai01:/#


which as you can see is only 5% full. At the moment it works fine. But 
when it gets to anywhere between 15% and 50% full it will return an 
error indicating that the filesystem is full and can't be written to any 
more. This seems to happen more & more... The last 4 months it's been 
fine. Then last week I managed to get just over 4000 files in there 
before it happened. Yesterday it was just over 2000, and today it failed 
with only 1200 files in it...

Anyone know why? Anything I can do?

TIA

Hamish.