Is it advisable to clear buffer cache in Production?

Hi

Currently we are restarting the server daily once. else when the users start using the application for a long time (around 24 hours but not more than 36 hours) database is getting down.I think this problem is due to the lack of memory space.

In SAW(server administration work bench) we can see the usage as below.Used memory and Available memory will be changing in each second but I guess database is getting down when the available memory is less/not available.


Details from SAW:

Heap memory allocated by VM: 530,907,136 bytes
Heap used memory in VM: 444,449,624 bytes
Available (free) memory in VM: 86,457,512 bytes


Is there any problem in flushing the buffer cache in production? Will it help anyways?

or Do I need to reduce the PGA?

Please let me know how can I resize SGA and PGA accordingly with in 4GB RAM.

Total SGA : 500 Mb
PGA : 100 Mb
Total users : 175 (but around 100 or less than that will access the application same time)
Total RAM : 4 GB


Thanks

I think I already saw a pretty similar post in a different section of the forum.

Any error messages on alertlog or client side?