routing table anamolies

[Shiraz Baig]

Now, here is a real problem.
We have 6 IP addresses. 203.147.165.112 to 119 with
netmask 255.255.255.248
We have used three. One for the mail server and one
for the DSL router and one for proxy server.

   Switch
 _______________
 |  |  |  | |  |
 |  |  |  | |   ---- DSL Router  ---- Internet
 |  |  |  | |        203.147.175.113
 |  |  |  | |
 |  |  |  |  ------- Proxy Server (multihomed)
 |  |  |  |          203.147.165.114
 |  |  |  |          192.168.10.4
 |  |  |  |   
 |  |  |  ----------Mail Server (multihomed)
 |  |  |            203.147.175.116
 |  |  |            192.168.10.3
 |  |  |
 |  |  -------- 192.168.10.5 (A) Linux machine
 |  ----------- 192.168.10.6 (B) windows machine
 ---------------- Hub & computers of address  
                   192.168.10.*

My Linux Machine shown as (A) in the diagram cannot 
connect to the internet. In fact, it does not even 
ping to DSL Router 203.147.175.113
On another windows macine (192.168.10.6) it
is happily accessing Internet thru proxy server.

Here is my routing table on Linux Machine.

Kernel IP routing table
Destination     Gateway  Genmask        Flags  MSS  S 
                            Window  irtt Iface
203.147.175.112 0.0.0.0  255.255.255.248 U        0   
                               0        0    eth0
192.168.10.0    0.0.0.0  255.255.255.0   U         0 
                               0        0    eth0
169.254.0.0     0.0.0.0  255.255.0.0     U         0
                               0        0    eth0
127.0.0.0       0.0.0.0  255.0.0.0       U         0 
                               0        0     lo
0.0.0.0         203.147.175.113 0.0.0.0  UG        0 
                               0        0     eth0

What is wrong with this table, and why can I not ping
203.147.175.113. 
I have done "echo 1 > /proc/sys/net/ipv4/ip_forward
I have also set proxy as 192.168.10.4.
By the way, I comapred this table with 
mail server (192.168.10.3) routing table. And it
resembles it competely. From othe mail server I can 
ping DSL router (113). But from Linux Machine 
I cannot do so.
Any suggestions?

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