Not receiving mail in my Yahoo account.

Why would you suspect spam as the cause? Unless you have recently changed your preferences regarding the filters used to screen your incoming e-mail, spam shouldn't be an issue.

Is your wife using the same computer to access her account? If not you may have a conflict with your anti-virus, anti-spyware or firewall software.

It could also be caused from any recent updates to your current browser

If your wife is using the same computer to access her account you should check all your preferences regardless. Inspect all your wife's preferences that she has on her account. Record them and change all yours to match.

In the past Yahoo e-mail has had a lot of similar problems in regards to users not receiving their e-mails. This problem though could happen to any e-mail service, web based or other wise. For that fact I believe it is prudent to have a second e-mail account from a separate e-mail service provider.
It's also a great way to keep spam and other junk separate from your important e-mails. Basicly you use one account for all your banking, credit card purchases work and on-line bill payments. The second you use for web based subscriptions, joining forums and friends. When a problem like this happens you have access to a second account.

If changing your setting doesn't work first request help from Yahoo e-mail support and then respond back here with info such as your current web browser and what version it is ( click help it the menu, click about Internet Explorer or Firefox) and it will be listed on the small window that opens. Also include what software are you using if any in conjunction with your browser. Such as Outlook Express.
I hope something here helps.