SGA_TARGET causes ora-04030, 04031

Hi, I have a database(10.2.0.4) running on a Windows 2003 Server, 32bit. The server has 8G of Ram, When I set the SGA_target=1.5G and leave out the sga cache parameters, after a few days I get many ora-04031 and ora-04030 errors. However, if I leave out the SGA_TARGET parameter and hard code the sga cache parameters(total 1.5G) , I never get these errors. Why ?

(from Metalink note)

* SGA components too small for workload
* Auto-tuning issues
* Fragmentation due to application design
* Bug/leaks in memory allocations

Please go through the below metalink URL and find the note relavent to your issue.

https://support.oracle.com/CSP/ui/fl...ource=KB%29%29

Thanks,