Its sad to say that this eventually happened. Its not that I did not anticipated it, but rather sad that after months of debugging and help from both Microsoft and Bullguard, I did not find a easy solution to resolve this.
Here is some background of what had happened. Recently, after the launch, I had decided to upgrade to Windows Home Server 2011 (Despite some features are gone such as Drive Extender). I had been using Bullguard Internet Suite all along prior to this when I was with WHS v1. However, I notice that once I had upgraded and reinstalled the WHS Clients on my desktops and laptops, only 1 of them actually works. The rest of them simply indicate that it cannot connect to the WHS 2001 Server and the server say the same thing about the client. As such, backup and some other functions such as monitoring etc are effectively crippled.
I had been bearing with this, while meantime, I kick started the support with Microsoft, which was my fault that I did not follow through because they had required for all my server's log. Due to privacy issue, I decided that I did not like that idea. At the same time, I contacted Bullguard which went in a spiral and eventually into the blackhole when they said they will get their engineer to take a look at it. Perhaps not many of their customer actually uses WHS 2011. OR plain fact is that people just accept it that these 2 don't mix and choose not to have them together.
Finally, after month of waiting, I decided that I will give up and dump Bullguard. I could try out some of the free solution out there, or buy one that actually works, but I probably won't pay easily now knowing that even commercial Anti Malware may actually not work, despite all they claim for the WHS Client.
So far, what have I tried? I found a free Personal Firewall known as PrivateFirewall (http://www.privacyware.com/personal_firewall.html) and it did actually work very well. Upon reboot, the WHS Client immediately got connected and monitoring, backup status are available. However, although the firewall make claims of blocking malware, it actually doesn't detects them as it does not come with a anti malware module. It only blocks any malware from connecting outside when it tries to.
So, I added a anti malware component to it. I choose Lavesoft's Ad-aware Free Internet Security 9.0 (http://www.lavasoft.com/products/ad_aware_free.php). Don't be confused that it say Internet Security that it will include a Firewall. It doesn't. At least the Free version does not. This however, fits nicely into my solution as it provides the missing anti malware component to PrivateFirewall. I installed this and tried out some checking and backup. No problem with WHS 2011 client software.
At randomly choosing 2 (pretty good) security software and it does not interfere with WHS, I suppose I can conclude that its not WHS at fault. I guess it is also unfortunate that Bullguard could not work as I pretty like it so far as it provided quite a complete suite of functions including vulnerability assessment (via software version). However, I guess they did not manage to test it with a wide enough range of applications and it eventually lead to this. Guess it only a matter of time I will give up, even though I still have a good half year subscriptions left.