My PC Mac address changed (Broadcom NetLink)

Hi all

I am a bit puzzled:

my mac address recently changed from

a4:ba:db:xx:xx:xx

 to

00:10:18:XX:XX:XX

I was always connected to a Dir655 router.

I have no issues at all with conectivity to internet.

could you please tell me:

1) If there any risk associated with an MAC adress change ?

2) What could explain that change of mac address?

Thank you,

Ben

System Information report written at: 04/05/11 23:12:07
Name [00000018] Broadcom NetLink (TM) Gigabit Ethernet 
Adapter Type Ethernet 802.3 
Product Type Broadcom NetLink (TM) Gigabit Ethernet 
Installed Yes 
PNP Device ID [DELETED BY BLACHANC]
Last Reset 4/5/2011 10:33 PM 
Index 18 
Service Name [DELETED BY BLACHANC] 
IP Address [DELETED BY BLACHANC]
IP Subnet [DELETED BY BLACHANC] 
Default IP Gateway [DELETED BY BLACHANC] 
DHCP Enabled Yes 
DHCP Server [DELETED BY BLACHANC]
DHCP Lease Expires 4/6/2011 10:34 PM 
DHCP Lease Obtained 4/5/2011 10:34 PM 
MAC Address 00:10:18:XX:XX:XX 
Memory Address 0xFBFF0000-0xFBFFFFFF 
IRQ Channel IRQ 4294967294 
Driver c:\windows\system32\drivers\k57nd60a.sys (12.4.0.3, 313.54 KB (321,064 bytes), 3/13/2010 12:30 PM)