Vista Business Crashing

Hi Friends,

I have a small home network,

Vista Laptop -----> D-Link Ethernet Router <-------- XP Home SP2
Laptop

On the XP laptop, there is a Western Digital External Hard disk,
which
I have shared through the home network.

The problems I face,

The network connection between the home PCs is very intermittent.. It
works, and then it doesn't ... No idea why it stops. But once I do a
ping -a to the xp laptop, the connections are restored.

When I can access the shared drives, copying of files to and fro
works
fine.. but slow..

However, When I tried to run a program (residing on shared drives),
Vista treats me with the blue screen... a crash...

Please help...

regards
raghav..