Solaris

why is this error message keeps coming once every month. Is this a serious problem?
In the /var/adm/messages file
Nov 26 06:10:42 ids-ldap07 px: [ID 280208 kern.warning] WARNING: PCI Express error report:
Nov 26 06:10:42 ids-ldap07 device_path = /pci@1e,600000/pci@0/pci@8, msg_code = 0x30, req_id = 0x340, Nov 26 06:10:42 ids-ldap07 px: [ID 772726 kern.warning] WARNING: sts_reg = 0x10, sts_sreg = 0x0, dev_sts_reg = 0x1 Nov
26 06:10:42 ids-ldap07 aer_ce = 0x1000, aer_ue = 0x0, are_ctl = 0xbf, Nov 26
06:10:42 ids-ldap07 px: [ID 311148 kern.warning] WARNING: aer_h1 = 0x45000001, aer_h2 = 0x1003, aer_h3 = 0x7080004, aer_h4 = 0x0, Nov 26
06:10:42 ids-ldap07 px: [ID 660983 kern.warning] WARNING: saer_ue = 0x0,
saer_h1 = 0x0, saer_h2 = 0x0 Nov 26 06:10:42 ids-ldap07 saer_h3 = 0x0,
saer_h4 = 0x0, severity = minor

I wasn't sure until I saw in the output:
Until someone has a better answer, I'd say 'no'.

I saw this article but not sure if this is relevant
[Xen-changelog] [linux-2.6.18-xen] PCI-Express AER implemetation - Xen Source

It's only relevant if you're running a XEN kernel. It's possibly relevant if you're running the XEN hypervisor kernel. If you have no need for virtualizing your environment with XEN, just turn it off/unconfigure it. It's probably already not configured.

how do i turn it off?

Boot with a different kernel. Look in /etc/grub/grub.conf to see if the kernel image you from contains the letters "xen". Change to one that doesn't.

I have no such file /etc/grub/grub.conf