RAM upgrade causing reboots and freezes

Hi everyone,

I'm having several problems after adding ram to my PC, causing it to reboots
or not boot at all.

I run Win 98 on a Compaq Presario 5446. I've checked the manufacturer
specifications and it says my PC can have a max of 256 mb RAM, to be divided
as 2x128MB between the two DIMM slots.
I bought my PC a few years ago with 64MB PC100 SDRAM installed. A few weeks
ago I bought 64MB of secondhand RAM off ebay and it worked and 128 RAM made
a vast improvement to the PC.
So I bought 2 x 128MB of new RAM to get the max from my PC. I put it in,
same as before, but when I started the computer it only read as far as 64MB
and just froze. Everytime I restarted the computer it was the same.
I thought maybe one of the memory sticks was faulty and tried removing each
one in turn, but on these occasions when I started the PC it wouldn't read
or 'countdown' any memory and went straight to the normal boot process, and
when Windows finally started it would reboot constantly.
I've had to slot in the original 64MB that came with the PC just to get the
PC to work. I just spent £40 (about $65) on these 2 memory modules and the
smallprint says it's a 'no refund' policy - in other words, if anything goes
wrong it must be because I chose the wrong type of memory or something.
Below I have the manufacturer's description of the memory stick(s) I bought,
and below that, what Compaq says about the type of memory needed for my PC:

(The memory modules I bought):

Module Size: 128MB
Package: 168-pin DIMM
Featu SDRAM, PC100
Configuration: 16Meg x 64
DIMM Type: Unbuffered
Error Checking: Non-Parity
Voltage: 3.3V
SDRAM Timings: CL=3


(My PC's specifications):

Memory Max - 256 MB
DIMM Memory Speed - 100 MHz CL3
Memory Type - Non-Parity
Dimm Module Type - Gold Contact
Number of Pins: 168
Max DIMM Capacity: 128 MB
Ram Type: 100 MHz SDRAM
Memory - In Slots: 64 MB
Total Memory Slots: Two

*Note: Primary path is to use the largest DIMM possible [i.e. (one) 128MB
DIMM with (two) 64MB DIMMs used only as backup]
**Note: CL2 Memory may also be used.
***Note: All DIMMs must support Serial Presence Detect (SPD) Revi

Can someone tell me if I have missed something and it is my mistake?

Thanks in advance,

Joanna