SCO Unix Network Hang

Hi All,
We have a SCO OpenServer 5.0.7 server in our office. Lately (past week) it has been hanging very roughly every 12 hours, and I need to reboot. The reboot seems to clear it up, and it runs fine, for a while.  We have 2 remote NFS shares mounted to the local file system, and the box also serves several samba shares. When the system begins to hang, these become unreachable (NFS shares from SCO, Samba shares from remote systems). We have about 50 users logging in at a time to our foxbase applications. Sometimes (I think if not rebooted quick enough) it stops responding to any network protocol (ssh, telnet, etc.).

Here is the netstat -m from before the last reboot (this was fairly deep into the hang)
streams allocation:
                                             config    alloc     free       total      max     fail
stream                                8448      202     8246        2464      202        0
queues                                  908      413      495        4939      413        0
mblks                                 8634     8164      470    26890848     8599        0
buffer headers                  9018     8568      450      308777     8969        0
class  1,     64 bytes         396       74      322    10407791      393        0
class  2,    128 bytes         50       20       30     2273073       76        0
class  3,    256 bytes         44       28       16     5951744      585        0
class  4,    512 bytes         14       10        4       34800       58        1
class  5,   1024 bytes       31        0       31       38453       54        3
class  6,   2048 bytes      7310     7309        1     2284286     7310      804
class  7,   4096 bytes       532      532        0       15352      585 43361300
class  8,   8192 bytes        0        0        0      114823        9       47
class  9,  16384 bytes        0        0        0      224169        3       43
class 10,  32768 bytes        0        0        0      154546        3      893
class 11,  65536 bytes        0        0        0        1830        3       54
class 12, 131072 bytes        0        0        0           0        0        0
class 13, 262144 bytes        0        0        0           0        0        0
class 14, 524288 bytes        0        0        0           0        0        0
total configured streams memory: 17024.00KB
streams memory in use: 17129.64KB
maximum streams memory used: 18012.29KB


I get this error message repeated quite a bit:
WARNING: allocb failed - NSTRPAGES exceeded


I am out of ideas where to look next, any help is greatly appreciated. Thank you.