I have a problem with new server.. I use VPS Centos with 1GB of ram and I use wordpress CMS.

The traffic <100 visitor/hour, but the apache have high load and make the server hang with zero free of ram and can't connect through ssh. I should reboot the vps to make it works

here is the load on Apache looks like

Tasks:  66 total,   1 running,  65 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.6%us, 12.3%sy,  0.0%ni, 48.1%id, 23.0%wa,  4.8%hi, 10.2%si,  0.0%
Mem:   1018776k total,   116620k used,   902156k free,     1236k buffers
Swap:  1048568k total,    1013052k used,  35516k free,    26628k cached
2949 apache    20   0  459m  42m 3732 D  3.0  4.2   0:09.23 httpd           
2959 apache    20   0  460m  29m 3744 D  2.0  3.0   0:02.72 httpd           
2968 apache    20   0  460m  26m 3808 D  2.0  2.6   0:02.27 httpd            
2972 apache    20   0  460m  24m 3784 D  2.0  2.5   0:02.44 httpd           
2986 apache    20   0  460m  29m 3784 R  2.0  2.9   0:02.40 httpd            
2969 apache    20   0  458m  29m 3864 D  1.6  3.0   0:02.63 httpd           
2974 apache    20   0  460m  25m 3820 D  1.6  2.6   0:02.43 httpd            
2990 apache    20   0  460m  23m 3920 D  1.6  2.4   0:02.36 httpd           
2994 apache    20   0  460m  31m 3756 D  1.6  3.2   0:02.62 httpd            
2956 apache    20   0  460m  26m 3740 D  1.3  2.7   0:02.73 httpd           
2957 apache    20   0  465m  22m 3644 D  1.3  2.3   0:02.80 httpd            
2967 apache    20   0  458m  24m 3764 D  1.3  2.5   0:02.60 httpd           
2970 apache    20   0  463m  25m 3764 D  1.3  2.6   0:03.07 httpd            
2971 apache    20   0  451m  22m 3792 D  1.3  2.3   0:02.47 httpd           
2973 apache    20   0  458m  25m 3768 D  1.3  2.6   0:02.52 httpd            
2987 apache    20   0  465m  20m 3772 D  1.3  2.1   0:03.02 httpd  

But sometimes the server have uptime more than 5-10hrs but after that the problems start